I  B 

OF  THE 

UNIVERSITY 
OF    ILLINOIS 


G30.T 


cop 


.  2, 


AGRICULTURE 


NON  CIRCULATING 

CHECK  FOR  UNBOUND 
CmCULATING  COPY 


UNIVERSITY  OF  ILLINOIS 

Agricultural  Experiment  Station 


BULLETIN  No.  300 


LESSONS  FROM  THE  MORROW 

PLOTS 

By  E.  E.  DETURK,  F.  C.  BAUER,  AND  L.  H.  SMITH 


URBANA,  ILLINOIS,  DECEMBER,  1927 


FOREWORD 

Whenever  it  develops  that  some  one  has  been  able  to  see 
across  a  half  century  to  what  facts  are  likely  to  be  needed  at  that 
time,  and  patiently  and  painstakingly  set  about  securing  those 
facts,  it  should  be  noted.  The  history  of  the  Morrow  plots  is  the 
story  of  the  results  of  such  foresight. 

The  planning  of  these  plots  is  all  the  more  remarkable  be- 
cause it  was  done  at  a  time  when  the  Agricultural  Experiment 
Stations  of  the  country  were  young  and  the  pressure  was  for 
investigations  that  would  yield  quick  returns.  Most  intimately 
connected  with  the  history  of  these  plots  are  the  names  of  Manley 
Miles,  first  professor  of  agriculture;  George  E.  Morrow,  pro- 
fessor of  agriculture  from  1876  to  1894;  Eugene  Davenport, 
dean  emeritus  of  the  College  of  Agriculture  and  for  twenty-eight 
years  director  of  the  Agricultural  Experiment  Station ;  and  Cyril 
George  Hopkins,  who  for  twenty-five  years  devoted  himself  un- 
tiringly to  furthering  the  principle  of  a  system  of  permanent  soil 
fertility. 

Begun  fifty-two  years  ago,  these  investigations  on  the  Mor- 
row plots  throw  light  on  fundamental  questions  of  soil  fertility  as 
vital  today 'as  any  which  farmers  are  asking.  For  instance :  What 
will  continuous  cropping  do  for  fertile  prairie  soils  which  used 
to  be  considered  everlasting  in  fertility?  What  comparative  re- 
sults may  be  anticipated  over  a  series  of  years  from  rotation 
systems  supplemented  with  soil  treatment  and  rotations  without 
additional  applications  of  plant  food?  Admitting  the  desirability 
of  doing  so,  can  I  afford  to  leave  my  farm  for  posterity  as 
productive  as  when  I  found  it  and  took  over  its  management? 

It  is  my  privilege  to  join  with  the  farmers  of  Illinois  in 
grateful  acknowledgment  to  the  men  who  had  the  vision  to  plan 
.and  to  those  who  have  had  the  persistence  to  carry  thru  these 
studies.  Another  period  of  fifty  years  may  yield  even  more 
valuable  information  than  is  presented  here. 


Director 


LESSONS  FROM  THE  MORROW  PLOTS 

By  E.  E.  DETURK,  F.  C.  BAUER,  AND  L.  H.  SMITH' 

To  the  hundreds  of  visitors  who  come  each  year  to  the  College  of 
Agriculture  of  the  University  of  Illinois,  the  Morrow  plots  are  a  fa- 
miliar sight.  To  other  hundreds  who  have  not  seen  them  they  have 
become  familiar  thru  reputation.  To  anyone  who  will  study  these  plots 
and  their  records  they  stand  as  a  monument,  marking  the  tragedy  of 
soil  exhaustion — a  tragedy  not  so  strikingly  dramatic  as  are  many  of 
the  great  catastrophes  of  history  but  nevertheless  as  burdened  with 
meaning.  The  impoverishment  of  the  fertile  soils  of  a  country  is  ob- 
scured from  the  eyes  of  many,  not  only  because  of  its  imperceptible 
advance,  seasons  of  plenty  being  interspersed  with  the  lean  years,  but 
also  because  of  the  inherited  belief  that  naturally  rich  soils  are  inex- 
haustible, a  belief  which  oftentimes  is  not  easily  relinquished. 

The  Morrow  plots  tell  also  the  story  of  Nature's  eternal  persistence 
in  maintaining  production  where  man  has  carried  his  share  of  the  re- 
sponsibility in  providing  suitable  soil  conditions.  The  records  of  these 
plots,  covering  thirty-nine  years,  like  those  of  the  oldest  fertility 
plots  in  the  world  at  the  Rothamsted  Experiment  Station  in  England 
covering  a  period  of  eighty-four  years,  point  to  the  possibility  of  main- 
taining crop  production  at  an  even  higher  level  than  that  of  the  virgin 
soil. 

EARLY  HISTORY  AND  MANAGEMENT 

The  Morrow  plots  are  located  on  the  campus  of  the  University 
of  Illinois  directly  north  of  the  New  Agricultural  Building.  The  soil 
on  which  these  plots  are  located  is  classified  by  the  Soil  Survey  of  the 
Illinois  Agricultural  Experiment  Station  as  Brown  Silt  Loam,  and 
by  the  United  States  Soil  Survey  as  Muscatine  silt  loam.  It  is 
naturally  a  productive  soil  and  is  representative  of  a  vast  area  of 
prairie  land  in  central  and  northern  Illinois. 

There  has  been  some  uncertainty  regarding  the  exact  date  of  the 
establishment  of  these  plots,  but  statements  found  in  various  records 
of  the  Experiment  Station  may  be  taken  as  furnishing  fairly  con- 
clusive evidence  that  these,  the  oldest  experimental  soil  plots  in  Amer- 
ica, have  been  in  continuous  operation  since  1876.  Thus  the  corn 
crop  just  harvested  on  Plot  3  (1927)  is  the  fifty-second  corn  crop 
grown  consecutively  on  this  plot,  while  the  rotations  on  the  other  two 
plots  have  been  continued  the  same  length  of  time,  except  for  the 
modification  in  one  as  noted  below. 


JE.  E.  DETURK,  Chief  in  Soil  Technology,  in  charge  of  soil  analysis  of  the  Soil  Survey; 
F.  C.  BAUER,  Chief  of  Soil  Experiment  Fields;  L.  H.  SMITH,  Chief  in  charge  of  the  publi- 
cations of  the  Soil  Survey. 

For  the  economic  interpretation  of  the  Morrow  plots  data,  pages  131  to  136,  including 
the  selection  of  the  cost  data  on  which  that  discussion  is  based,  the  authors  are  indebted  to 
Professors  H.  C.  M.  Case  and  R.  H.  Wilcox,  of  the  Department  of  Farm  Organization  and 
Management. 

107 


108 


BULLETIN  No.  300 


[December, 


The  series  as  originally  laid  out  consisted  of  10  half-acre  plots, 
each  5  rods  by  16  rods.  The  growth  of  the  University  campus,  how- 
ever, necessitated  subsequent  reduction  of  the  area.  In  1895  the 
astronomical  observatory  was  built  on  Plots  1  and  2,  and  in  1903  all 
the  other  plots  except  Nos.  3,  4,  and  5  were  discontinued  and  the  land 
seeded  down  to  lawn.  During  the  following  year,  1904,  these  remain- 
ing plots  were  cut  down  to  9 
rods  in  length.  At  the  same  time 
division  strips  half  a  rod  wide 
were  established  between  the  plots, 
and  a  cropped  border  one-fourth 
rod  wide  left  around  the  plotted 
area.  Furthermore,  each  of  the 
three  plots  was  divided  into  four 
quarters  by  half -rod  division  strips 
thru  the  center  in  both  directions. 
Thus  each  of  the  three  original 
half-acre  plots  now  consists  of 
four  separate  plots,  each  2  rods 
wide  north  and  south  by  4  rods 
long  east  and  west  and  containing 
one-twentieth  of  an  acre.1  At  the 
time  of  the  subdivision  of  the 
plots  the  land  was  tile-drained,  a 
line  of  4-inch  tile  being  laid  in  the 
half -rod  division  strips  between 
the  north  and  south  halves  of  each 
of  the  three  original  plots.  Thus 
one  line  of  tile  lies  adjacent  to 
each  of  the  twelve  present  plots, 
as  indicated  by  the  broken  lines  in 
Fig.  1. 

No  record  of  crop  yields  from 
the  various  plots  is  available  prior 
to  1888,  the  year  in  which  the  Ex- 
periment Station  was  established. 
In  the  earlier  reports  made  by 
Professor  George  E.  Morrow  and 
his  associates,  no  reason  is  stated 
as  to  why  yields  were  not  given. 
The  records  do,  however,  state 
clearly  the  important  fact  that  the 


i  

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3  NW 
0 

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0 

\ 

I 

33W 
ML  aP 

3  J£ 
ML  aP 

^ 

4-MW 
O 

\ 

4  NE 
^ 

X 

4SW 
ML  aP 

'\ 

ML  e\ 

V 

> 

SflfW 
O 

\ 

5  /V£ 
^Q. 

v 

~- 

5SW 
MLuP 

SS£\ 
ML  oP 

\ 

% 

V 

Contour  Interval  -  I  Foot 
o     zo    40  SO        I6O 

i 1        i  i  ' 

Scale  of  Feet 

FIG.  1. — PLAN  OF  THE  MORROW  PLOTS 
The  Morrow  plots  are  situated  on 
Brown  Silt  Loam,  a  soil  type  which 
is  representative  of  vast  areas  of 
corn-belt  land.  The  surface  of  the 
plots  is  nearly  level,  and  the  area  is 
drained  by  a  tile  line  adjacent  to  each 
plot.  Corn  is  grown  every  year  on 
the  four  small  plots  numbered  3.  The 
4's  carry  a  two-year  rotation  of  corn 
and  oats,  while  a  three-year  rotation 
of  corn,  oats,  and  clover  occupies  the 
plots  at  the  south,  numbered  5. 


'The  four  plots  thus  formed  from  the  original  Plot  3  are  numbered  3-NE, 
3-NW,  3-SE,  and  3-SW,  and  similar  numbering  is  used  for  the  plots  formed  from 
Plots  4  and  5. 


LESSONS  FROM  THE  MORROW  PLOTS  109 

cropping  systems  as  originally  planned  were  maintained  during  those 
early  years  and  that  no  manures  or  fertilizers  of  any  kind  were 
applied. 

Cropping  Systems  Practiced 

Three  different  cropping  systems  are  practiced  on  the  plots  of 
the  Morrow  series.  Plot  3,  to  the  north,  has  grown  corn^  every  year 
from  the  beginning  of  the  experiment  up  to  the  present  time.  Plot 
4,  in  the  center,  has  grown  corn  and  oats  alternately  during  the  same 
time,  while  Plot  5,  to  the  south,  has  been  cropped  as  follows :  Up 
to  and  including  1899  a  rotation  was  grown  consisting  of  corn  for  two 
years,  oats  one  year,  meadow  (clover,  timothy,  or  both)  three  years. 
In  1900  this  plot  (Plot  5)  was  used  for  oats  variety  trials.  Begin- 
ning in  1901  a  three-year  rotation  of  corn,  oats,  and  red  clover  was 
adopted  and  has  been  continued  uninterrupted  to  the  present  time, 
except  that  where  clover  failed  cowpeas  were  substituted  in  1906  and 
soybeans  in  1912  and  1915. 

Disposal  of  Crops  Grown 

On  all  NE  and  NW  plots  the  grain,  straw,  stalks,  and  hay  have 
been  removed.  No  residues  except  stubble  and  roots  have  been  re- 
turned either  directly  or  in  manure. 

On  Plots  3-SE  and  3-SW,  which  are  cropped  continuously  to 
corn,  the  stalks  and  grain  have  been  harvested,  and  to  each  plot  has 
been  applied  an  amount  of  manure  which  could  reasonably  be  expected 
to  have  been  produced  if  the  produce  of  the  plot  had  been  used  as  feed 
and  bedding,  as  explained  in  the  paragraph  on  manure  applications 
(page  110).  For  some  years  legume  cover  crops  were  seeded  in  the 
corn  at  the  last  cultivation,  but  the  failures  were  so  frequent  that  the 
practice  was  discontinued. 

On  Plots  4-SE  and  4-SW,  on  which  a  corn  and  oats  rotation  is 
followed,  the  grain,  straw,  and  stalks  of  both  crops  are  removed  and 
manure  returned  to  the  respective  plots  according  to  the  plan  followed 
on  Plots  3-SE  and  3-SW.  In  addition,  beginning  in  1904,  catch  crops 
were  seeded  in  the  oats  and  plowed  down  the  following  spring  for  corn. 
Starting  in  1912  this  catch  crop  was  a  clover  mixture,  containing  some 
sweet  clover.  In  1914,  15  pounds  of  sweet  clover  and  5  pounds  of 
alsike  an  acre  were  seeded.  The  crop,  however,  was  mainly  alsike. 
In  1916  a  mixture  of  sweet  clover  and  red  clover  was  seeded.  Red 
clover  predominated  in  the  crop  plowed  under  the  following  spring. 
Since  1916  sweet  clover  alone  has  been  used,  and  satisfactory  growth 
has  been  secured  in  practically  all  cases. 

On  Plots  5-SE  and  5-SW,  cropped  to  corn,  oats,  and  clover  in 
rotation,  the  stalks,  straw,  and  grain  as  well  as  clover  hay  are  removed 
and  manure  is  returned  as  indicated  above.  There  is  no  place  in  this 


110 


BULLETIN  No.  300 


[December, 


rotation  for  a  catch  crop,  since  the  red  clover  sod  is  plowed  down 
for  corn. 

Application  of  Fertilizing  Materials 

Previous  to  the  subdivision  of  the  original  plots  in  1904  no 
manure  or  fertilizers  of  any  kind  were  applied.  Since  that  time  the 
NE  and  NW  plots  have  been  continued  without  treatment,  each  pair 
being  duplicates,  identical  except  for  natural  soil  variation.  This  has 
made  it  possible  to  continue  the  study  of  the  effects  of  the  different 
cropping  systems  without  fertilizers. 

On  the  SE  and  SW  plots  a  plan  of  fertilization  was  adopted 
which  included  the  return  of  farm  manure  and  also  the  addition  of 
limestone  and  phosphate.  The  details  of  these  treatments  follow. 

Manure. — Beginning  in  1904  manure  has  been  applied  to  all  SE 
and  SW  plots.  Until  1909  the  applications  were  made  at  the  rate  of  2 
tons  an  acre  a  year ;  since  then  all  applications  have  been  in  direct  pro- 
portion to  the  crops  removed  from  the  respective  plots ;  that  is,  in 
amounts  equal  in  weight  to  the  air-dry  weight  of  the  crops  removed. 


TABLE  1. — MANURE  APPLIED  TO  MORROW  PLOTS 

(Tons  per  acre) 


Plot  3 

Plot  4 

PlotS 

SW 

SE 

SW 

SE 

SW 

SE 

Total,  1904  thru  1926  

71.4 
3.10 

76.0 
3.30 

70.3 
3.06 

75.3 
3.27 

66.3 
2.88 

69.3 
3.01 

Average  yearly  amount  

In  all  cases  the  manure  is  applied  preceding  the  corn  crop;  hence 
manure  is  applied  annually  to  Plots  3-SE  and  3-SW,  once  in  two 
years  to  Plots  4-SE  and  4-SW,  and  once  in  three  years  to  Plots  5-SE 
and  5-SW.  The  total  amounts  applied  to  these  plots  from  1904  thru 
1926  are  given  in  Table  1. 

Limestone. — In  1904  ground  limestone  was  applied  to  the  SE 
and  SW  plots  at  the  rate  of  1,704  pounds  an  acre,  and  in  1919  a 
further  application  at  the  rate  of  5  tons  an  acre  was  made.  The  total 
limestone  application  made  to  each  of  the  treated  plots  in  the  twenty- 
three  years  is  thus  5.85  tons  an  acre.  At  the  average  price  of  $2  a  ton, 
this  would  cost  $11.70.  The  average  annual  acre  cost  would  there- 
fore be  51  cents. 

Phosphate. — From  1904  thru  1918  steamed  bone  meal  was 
applied  yearly  to  the  SE  plots  at  the  rate  of  200  pounds  an  acre.  During 
the  same  years  rock  phosphate  was  applied  to  the  SW  plots  at  three 
times  the  rate  used  for  bone  meal,  or  at  the  annual  acre  rate  of  600 
pounds.  In  1919  the  annual  rate  of  bone  meal  was  reduced  to  50 


1927]  LESSONS  FROM  THE  MORROW  PLOTS  111 

pounds  an  acre,  and  the  application  of  rock  phosphate  was  reduced 
to  the  rate  of  200  pounds  an  acre,  so  that  the  ratio  of  rock  phosphate 
to  bone  meal  now  stands  4  to  1.  At  the  same  time  enough  additional 
rock  phosphate  was  applied  to  bring  the  total  application  for  the  pre- 
ceding fourteen  years  up  to  four  times  the  total  amount  of  bone  meal 
which  had  been  applied  during  the  same  period.  In  1925  it  was  decided 
to  discontinue  the  further  application  of  phosphates  for  an  indefinite 
period. 

Prior  to  1918  the  phosphates  were  applied  on  Plots  3  and  4  once 
in  two  years,  the  year  preceding  that  in  which  corn  appeared  on  Plot 
4;  and  on  Plot  5  also  the  year  preceding  the  corn  crop,  or  once  in 
three  years.  In  1918  it  was  decided  to  apply  the  phosphates  to  all 
three  plots  only  once  in  six  years,  in  the  winter  preceding  the  corn  crop 
which  appears  simultaneously  on  all  plots. 

The  total  rock  phosphate  application  made  in  twenty-three  years 
to  each  of  the  SW  plots  has  been  13,200  pounds  an  acre.  This  at  $10 
a  ton,  an  average  price  for  the  past  decade,  would  cost  $66,  or  $2.87 
an  acre  annually.  The  bone  meal  application,  3,300  pounds  an  acre 
for  the  twenty-three  years,  at  $40  a  ton,  an  average  price,  would  cost 
the  same  on  the  acre  basis  as  the  rock  phosphate.  The  profitableness 
of  the  treatments  and  of  the  different  cropping  systems  is  discussed 
on  pages  131-136.  For  the  purposes  of  this  study  the  cost  of  the 
various  fertilizing  materials  is  reckoned  uniformly  for  twenty-three 
years  altho  as  a  matter  of  fact  certain  of  the  applications  have  been  in 
effect  for  only  twenty-two  crops. 

EFFECTS  OF  ROTATION  AND  FERTILIZATION  UPON  CROP  YIELDS 

The  most  important  lesson  to  be  drawn  from  the  Morrow  plots 
is  to  be  found  in  the  crop  yields  obtained  under  the  different  systems 
of  soil  management.  These  yield  records  extend  over  a  period 
of  thirty-nine  years.  During  the  first  sixteen  years  all  yields  were 
from  untreated  soil,  no  fertilization  of  any  kind  being  practiced, 
as  previously  stated.  Thruout  the  following  twenty-three  years  the 
yields  were  from  both  fertilized  and  unfertilized  crops. 

Producing  Power  Wanes  Under  Continuous  Corn  Growing 

The  fact  that  continuous  cropping  to  the  same  crop  lowers  the 
productive  power  of  the  soil  is  generally  recognized.  A  positive  proof 
of  this  fact  and  a  measure  of  the  amount  of  decrease  is  found  in  the 
yields  on  Plot  3-N,  where  corn  has  been  grown  continuously  (Table 
3).  Without  treatment  this  plot  in  the  second  period,  1904  thru  1926, 
yielded  14.6  bushels  an  acre  a  year  less  than  in  the  first  period,  1888 
thru  1903 ;  which  is  a  falling  off  of  more  than  one-third. 


112 


BULLETIN  No.  300 


[December, 


TABLE  2. — ANNUAL  ACRE  YIELDS  OF  CROPS  FROM  THE  MORROW  PLOTS 
(Yields  from  steamed  bone  meal  plots  are  combined  with  the  yields  from 

the  raw  rock  phosphate  plots.    The  separate  yields  are  given  in  Table  8,  pages 

138-139.) 


Year 

Soil 
treatment 
applied1 

Plot  3 

Corn 
every 
year 

Plot 
Two-year 

4 
rotation 

Plot  5 
Three-year  rotation 

Corn 

Oats 

Corn 

Oats 

Clover 

1879-87 
1888 
1889 
1890 
1891 
1892 
1893 
1894 
1895 
1896 
1897 
1898 
1899 
1900 
1901 
1902 
1903 

1904 
1905 
1906 
1907 
1908 
1909 
1910 
1911 
1912 
1913 
1914 
1915 
1916 
1917 
1918 
1919 
1920 
1921 
1922 
1923 
1924 
1925 
1926 

None  

bu. 

bu. 
49  .'5 

54  .'3 
33.2 

29  .'6 
41.6 
47  .'6 

44.'  4 
33.7 
35.9 

50.  '6 
44.9 

47.'  8 
87.6 

33  .'6 
64.8 

28.  '6 
46.3 

29.'  2 
25.0 

49  .'6 
81.2 

48  .'4 
81.4 

30.'  8 
66.2 

30  .'6 
68.4 

17.'2 
46.4 

26.  -7 
39.5 

bu. 
37.  '4 

37.  'i 
57.  '2 
34  .'5 

ii.'s 

56.  '3 

17.5 
25.3 

34  .'7 
52.4 

32.  '9 
45.0 

33.'  8 
59.4 

55  .'6 
81.0 

33  .'6 
58.2 

37.  "S 
64.7 

27.  ~2 
59.3 

37.  '2 
51.6 

39  .'3 
55.8 

36  .'6 
68.5 

22  .'9 
76.3 

feu. 

bu. 

tons 

64» 
17» 

.53» 

85» 

None  

54.3 
43.2 
48.7 
28.6 
33.1 
21.7 
34.8 
42.2 
62.3 
40.1 
18.1 
50.1 
48.0 
23.7 
60.2 
26.0 

21.5 
17.1 
24.8 
31.4 
27.1 
35.8 
29.0 
48.7 
13.4 
28.0 
26.6 
31.6 
35.9 
54.6 
21.9 
31.5 
43.2 
64.2 
19.4 
32.0 
31.6 
39.4 
40.0 
66.0 
11.2 
10.8 
40.0 
78.0 
13.6 
32.6 
24.0 
43.4 
28.2 
54.4 
19.8 
42.2 
24.6 
39.4 
15.0 
31.4 
28.0 
38.0 
19.1 
45.4 
21.4 
35.4 

70  .'2 
34.1 

48.6 

65.  i 
22.2 

4.'  04 
1.51 
1.46 

None  

None  

None  

None  

None  

None      

None  

None  

None  

None  

None     

53.5 

None  

None  

34.3 

55.3 

72.7 

80.'  5 
93.6 

58.  '6 
83.3 

33.8 
47.8 

27.'  8 
40.6 

52.  '2 
70.8 

49  .'2 
65.3 

42.  i 
58.7 

54.6 

42  .'3 
50.6 

40  .'6 
44.4 

20  .'6 
38.0 

39.6 
60.4 

68.'  4 
86.9 

52.'  2 
69.7 

53.  '4 
66.6 

44.3 
85.0 

i.'ii 
i.'ii* 

1.74» 

'.'65  + 
1.73+1 

i.'35< 
1.70« 

i.'s4< 

1.96« 

2.'  58 
4.04 

'.'26  + 
1.33  + 

i.'83 
4.42' 

None  

None  

0  . 

MLP  

0  

MLP  

0  .  . 

MLP    

0  

MLP  
0  

MLP  

0  

MLP  

0  

MLP    

0  .  . 

MLP    . 

0  

MLP  

0  

MLP  

0  .  .  

MLP  

0  

MLP  

0  .  . 

MLP... 

0  .  . 

MLP.  . 

0  

MLP  

0  

MLP  

0  

MLP  

0  

MLP  

0  

MLP...    . 

0  

MLP... 

0  

MLP.  . 

0  .  . 

MLP... 

0  .  . 

MLP  

•Treatment  on  south  half  of  Plot  4  includes  legume  green  manure  beginning  in  1904. 
'Cowpea  hay  in  1906.     'Clover  seed  harvested  (bushels)  in  addition  to  hay. 
'Soybean  hay  in  1912  and  1915.     'Hay  contaminated  with  sweet  clover  in  1924. 


1927] 


113 


That  the  waning  yields  have  come  about  steadily  as  a  result  of 
soil  impairment  rather  than  seasonal  conditions  is  indicated  by  the 
decreasing  yields  in  four  successive  nine-year  periods.  For  the  first 
nine  years,  1888  thru  1896,  the  average  annual  yield  was  41  bushels 

TABLE  3. — SUMMARY  OF  YIELDS  FROM  MORROW  PLOTS  FROM  1888  TO  1926 

(Average  annual  yields  per  acre;  figures  in  italics  indicate  number  of  crops  grown) 


Years 

Soil  treatment 
applied1 

Plot3 

Corn 
every 
year 

Plot  4 
Two-year  rotation 

PlotS 
Three-year  rotation 

Corn            Oats 

Corn 

Oats 

Clover 

1888-1926 

None  

bu. 
39 
31.1 

bu.               bu. 
20                18 
38.0            37.3 

bu. 
12 
49.3 

bu. 
12 
45.9 

tons 

9 
1.64 

1888-1903 
1904-1926 

None   

16 
39.7 

23 
25.1 
40.5 

9                  6 
41.0             44.0 

11                 12 
35.6             34.0 
59.2             58.1 

4 
48.0 

8 
50.0 
66.6 

4 
47.6 

* 
45.1 
62.7 

4 
2.03 

7 
1.39» 
2.40* 

None  

MLP  

Percentage  increase  for 
treatment  

61.3 

66.3             70.8 

33.2 

39.0 

72.7 

'Treatment  on  the  south  half  of  Plot  4  includes  legume  green  manure  beginning  in  1904.     *Cowpea 
and  soybean  hay  included. 


of  corn.  This  was  followed  in  the  next  three  nine-year  periods  by 
average  yields  of  34.7,  27.6,  and  24  bushels  an  acre.  Further  evi- 
dence that  the  decline  in  yield  has  been  due  to  soil  impairment  rather 
than  climatic  conditions  is  shown  by  the  large  and  increasing  yields 
which  have  been  maintained  on  other  plots  during  the  same  years  by 
crop  rotation  and  fertilization. 

Crop  Rotation  Checks  Lowering  Yields 

In  the  corn  and  oats  rotation  the  corn  yields  without  soil  treat- 
ment (Plot  4-N)  have  been  reduced  from  41  bushels  an  acre  as  an 
annual  average  for  the  first  period,  to  35.6  bushels  in  the  last  period, 
a  reduction  of  only  5.4  bushels  (Table  3).  Thus  the  alternation  with 
oats  has  checked,  but  not  entirely  stopped,  the  downward  trend  of 
the  corn  yields. 

The  comparison  of  the  corn  and  oats  rotation  with  continuous 
corn  growing  can  be  made  more  accurately  by  comparing  the  corn 
yields  on  the  two  plots  during  the  years  when  both  plots  were  in  corn 
at  the  same  time,  thus  eliminating  any  possible  advantage  to  either 
plot  that  might  be  due  to  seasonal  differences.  We  find  that  as  an 
average  of  the  twenty  crops  grown  on  the  two  plots  in  the  same  years, 
both  without  fertilizers,  the  continuous-corn  plot  yielded  30.8  bushels 
an  acre,  while  in  the  corn  and  oats  rotation  the  yield  was  38.0  bushels, 
which  is  a  gain  of  7.2  bushels  an  acre  a  year. 


114  BULLETIN  No.  300  [December, 

The  three-year  rotation  without  soil  treatment  has  been  even  more 
effective  than  the  two-year  rotation  in  maintaining  crop  yields.  This 
is  dne,  at  least  in  part,  to  the  fact  that  the  third  crop  is  clover.  The 
corn  yields  in  the  first  period,  as  will  be  noted  from  Table  3,  aver- 
aged 48  bushels  an  acre  in  the  three-year  rotation,  as  compared  with 
41  bushels  in  the  two-year  rotation  of  corn  and  oats.  In  the  second 
period  the  yield  averaged  50.0  bushels  in  the  three-year  rotation  and 
35.6  bushels  in  the  two-year  rotation.  Thus  the  benefit  of  the  three- 
year  rotation  is  cumulative,  the  advantage  of  14.4  bushels  an  acre  a 
year  in  the  second  period  being  double  that  for  the  first  period. 

Looking  at  the  facts  from  a  somewhat  different  angle,  we  see 
that  on  both  the  continuous-corn  land  and  on  that  growing  the  two- 
year  rotation,  the  average  annual  corn  yields  have  fallen  off  14.6  and 
5.4  bushels  an  acre  respectively  in  the  second  period  as  compared  with 
the  first.  Where  the  clover  is  included  the  yield  does  not  fall  off  but 
increases  from  an  average  of  48  bushels  an  acre  to  50  bushels. 

While  the  yields  of  oats  on  Plots  4  and  5  are  not  so  striking  as 
those  of  corn,  they  tell  much  the  same  story  as  the  corn  yields. 

Fertilization  Does  Not  Replace  Rotation 

The  idea  is  held  by  many  farmers  that  a  sufficient  use  of  ferti- 
lizers can  solve  the  problem  of  maintaining  yields,  without  rotating 
crops.  The  yields  from  the  Morrow  plots  show  clearly  that  this  is  not 
the  case.  Crop  rotation  is  a  fundamental  part  of  soil  management,  as 
shown  above,  and  fertilizers  are  used  as  a  supplement  in  order  to  make 
good  the  deficiencies  in  the  soil,  whether  such  deficiencies  are  natural 
or  have  developed  as  a  result  of  cropping. 

Considering  only  the  fertilized  portion  of  the  Morrow  plots, 
decided  increases  in  yield  are  to  be  observed  as  a  result  of  crop  rota- 
tion. Corn  grown  continuously  on  this  fertilized  land  averaged  only 
40.5  bushels  an  acre  annually;  in  the  two-year  rotation  it  rose  to  59.2 
bushels ;  while  in  the  three-year  rotation,  which  includes  clover,  the 
average  yield  reached  66.6  bushels.  These  higher  yields  have  been 
obtained  on  the  two  rotation  plots  even  tho  all  three  plots  received  the 
full  soil  treatment,  and  in  the  case  of  Plot  5-S,  which  produced  the 
highest  yield,  both  cuttings  of  clover  were  removed  in  most  cases,  only 
the  sod  being  plowed  down  for  the  following  corn  crop. 

Clover  Demonstrates  Value  in  Maintaining  Yields 

The  importance  of  clovers  in  a  crop  rotation  for  the  maintenance 
of  a  satisfactory  level  of  production  can  scarcely  be  overstated.  Their 
value  is  demonstrated  in  the  two-year  rotation  on  Plot  4-S,  where 
sweet  clover  is  used  as  a  green-manure  crop  (see  page  109),  as  well 
as  on  Plots  5-S  and  5-N,  where  red  clover  is  used  as  one  of  the  full 
season  crops  in  the  three-year  rotation. 


1927]  LESSONS  FROM  THE  MORROW  PLOTS  115 

Since  1916  only  biennial  white  sweet  clover  (Melilotus  alba)  has 
been  used  on  Plot  4-S.  It  is  seeded  with  the  oats  in  the  spring  and 
in  the  following  spring  the  entire  clover  crop  is  plowed  down  for  corn. 
A  satisfactory  growth  is  practically  always  obtained,  the  amount  of 
clover  plowed  down  usually  being  equal  to  about  1%  tons  of  dry 
matter,  disregarding  the  roots,  which  are  nearly  if  not  quite  equal  in 
weight  to  the  tops  at  that  time  of  year. 

During  the  eleven  years  from  1904  thru  1914,  which  was  before 
the  adoption  of  sweet  clover  as  a  green  manure  on  this  plot,1  five 
crops  of  corn  were  grown  averaging  53.7  bushels  an  acre.  In  the 
next  twelve  years  six  more  crops  of  corn  were  grown  on  that  plot 
with  exactly  the  same  treatment  except  for  the  addition  of  the  sweet- 
clover  green-manure  crop,  and  the  average  yield  was  63.8  bushels,  or 
a  gain  amounting  to  10.1  bushels  arr  acre  a  year  for  the  years  in 
which  the  corn  followed  sweet  clover.  The  larger  yields  during  the 
second  period  were  due  largely  to  the  presence  of  sweet  clover  in 
the  rotation,  and  not  to  an  accidental  series  of  more  favorable  corn 
seasons.  This  is  apparent  from  the  fact  that  the  corn  yields  on  the 
untreated  plot  of  the  same  rotation  (Plot  4-N)  averaged  37.7  bushels 
for  the  earlier  period  and  33.8  bushels  for  the  next  twelve  years — a 
falling  off  of  3.9  bushels  during  the  same  years  in  which  the  sweet- 
clover  plot  gained  10.1  bushels. 

The  producing  capacity  of  this  treated  land,  Plot  4-S,  during 
twelve  years  of  sweet-clover  green  manuring,  has  attained  a  capacity 
(63.8  bushels  of  corn)  almost  equal  to  that  of  the  similar  land  in 
Plot  5-S,  which,  during  its  twenty-two  years  of  a  three-year  red-clover 
rotation,  has  averaged  66.6  bushels. 

Rotation  Without  Fertilization  Insufficient 

Even  good  rotations  cannot  maintain  crop  production  at  a  high 
level,  except  in  unusual  cases,  without  the  addition  of  supplementary 
materials,  either  limestone  or  fertilizing  materials  or  both.  In  the 
first  place  rotations  which  are  most  effective  in  maintaining  the  prod- 
uctivity of  the  soil  include  legumes.  Legumes  are  more  or  less  sensi- 
tive to  acid  soils,  and  this  necessitates  the  use  of  limestone  in  a  great 
many  cases  before  the  rotation  can  be  established. 

In  planning  the  modifications  made  on  the  Morrow  plots  in  1404, 
the  possible  necessity  of  fertilization  as  a  farm  practice  was  recog- 
nized, and  consequently  a  treatment  was  adopted  for  half  of  the  plots 
that  included  limestone,  manure,  and  phosphate,  as  described  on  pages 
110-111.  Unfortunately  there  was  not  sufficient  land  to  permit  each  of 


'As  previously  noted  (page  109)  no  sweet  clover  was  used  during  this 
period  except  in  1912  and  1914,  when  it  was  grown  in  a  mixture  with  alsike 
clover. 


116  BULLETIN  No.  300  [December, 

the  three  fertilizers  to  be  applied  separately.  Only  the  composite 
effect  of  the  entire  treatment,  therefore,  and  not  the  effect  of  the 
materials  used  separately,  can  be  studied  on  these  plots. 

The  results  of  this  experiment  can  leave  no  doubt  of  the  efficacy 
of  this  treatment  on  the  soil  type  here  concerned.  It  is  a  compara- 
tively easy  matter  to  increase  the  yields  on  exhausted  or  run-down 
soil  by  means  of  adequate  soil  treatment.  But  here  we  have  a  soil 
which  is  naturally  productive,  and  we  find  that  this  system  of  ferti- 
lization not  only  brings  up  the  yields  where  the  soil  has  been  depleted 
by  continuous  cropping,  but  has  produced  an  equally  large  increase 
in  a  rotation  which  maintained  the  untreated  corn  yields  at  an  average 
of  50  bushels.  The  average  crop  increases  for  the  twenty-three  years 
from  1904  thru  1926  range  from  33.2  percent  for  the  corn  on  Plot  5-S, 
to  72.7  percent  for  the  clover  on  the  same  plot  (Table  3).  In  some 
years  the  yields  of  all  crops  were  more  than  doubled  by  the  soil 
treatment. 

Trend  of  Production  as  Influenced  by  Rotation 
and  Soil  Treatment 

In  summing  up  this  discussion  of  the  productive  capacity  of  the 
soil  as  affected  by  the  different  systems  of  management,  it  may  be 
well  to  observe  the  general  direction  in  which  production  is  going. 

In  the  following  discussion  the  yields  are  given  in  money  values 
instead  of  bushels  or  tons.  This  is  done,  not  in  order  to  place  a  finan- 
cial interpretation  upon  the  results,  but  to  convert  the  results  into  a 
common  denominator  so  that  all  are  comparable.  The  prices  used 
are:  corn,  75  cents  a  bushel;  oats,  45  cents;  soybeans  (grown  where 
clover  failed  in  two  cases),  $1.50  a  bushel;  hay,  $15  a  ton,  and  clover 
seed,  $15  a  bushel. 

In  the  accompanying  curves  (Figs.  2  to  6)  the  values  of  the 
crops  from  the  various  plots  each  year  are  shown  by  the  zigzag  lines. 
These  values  vary  widely  from  year  to  year  because  of  seasonal  con- 
ditions. The  straight  lines  drawn  thru  the  zigzag  lines  show  the  trend, 
or  general  direction,  taken  by  the  annual  yields.1 

The  results  from  the  three  different  cropping  systems  on  the 
treated  land  are  compared  in  Fig.  2.  Not  only  are  the  financial 
returns  greater  in  the  two-crop  system  than  in  continuous  corn,  and 
still  greater  in  the  three-year  rotation,  but  these  differences  have  been 
maintained  consistently  thruout  the  period.  It  is  significant  that  in 
all  three  cropping  systems  where  the  land  is  treated  the  trends  are 
upward. 

'The  location  of  this  trend  line  is  determined  by  the  rrethod  of  least 
squares,  using  the  following  formulas:  (1)  Sum  y  =  sum  x  (m)  +  sum  (n)  ; 
(2)  sum  xy  =  sum  x*  (m)  +  sum  x  (n)  ;  in  which  y  =  observed  yields,  x  = 
successive  points  on  abscissa,  m  =  slope  of  line,  n  =  point  of  origin  of  straight 
line. 


1937} 


LESSONS  FROM  THE  MORROW  PLOTS 


117 


When  the  cropping  systems  on  the  untreated  plots  are  compared, 
a  different  situation  is  observed  (Fig.  3).  At  the  time  when  the  records 
were  started  (1888)  the  continuous-corn  land  was  producing  the  high- 
est financial  returns  ($31.81).  Since  at  the  beginning  of  the  experiment 
the  soil  of  all  the  plots  was  presumably  about  alike  in  productive  power, 
it  would  appear  that  this  early  advantage  in  financial  returns  from  the 
continuous  growing  of  corn  was  due  to  the  fact  that  corn  was  the  high- 


» SA    (\ 

I  I      .  I'  I  I     I 

fl    t  \   I 


Continuous   corn 

Corn,  oofs  rotation 

— --  Corn,  oars,  clover  rotation 


Corn  15* 
Oati  45' 
/lav  &I5 


1906 


/9I6 


I9ZO 


FIG.  2. — ANNUAL  CROP  VALUES  AND  TRENDS  IN  PRODUCING  POWER 

OF  THE  TREATED  LAND  OF  THE  MORROW  PLOTS 

The  use  of  manure,  limestone,  and  phosphate  has  kept  the  trend  of  produc- 
tion upward  for  twenty-three  years  in  all  three  cropping  systems,  as  indicated 
by  the  three  straight  lines  in  the  center  of  the  graph. 


Continuous  corn  Corn    75* 

Corn,  oats  rotation  Oats    45* 

Corn,  oats,  clover  rotation       Hay   t/5 


FIG.  3. — TREND  IN  PRODUCING  POWER  OF  THE  UNTREATED  LAND 

OF  THE  MORROW  PLOTS 

Without  soil  treatment,  production  declines  regardless  of  the  cropping  sys- 
tem followed.  The  decline  is  much  more  rapid  under  continuous  corn  than  where 
rotation  of  crops  is  practiced. 


118 


BULLETIN  No.  300 


[December, 


est  priced  crop  of  the  group.  The  introduction  of  oats,  a  crop  of  low 
value,  in  the  other  two  rotations  cut  down  the  financial  returns  so  long 
as  the  plots  all  remained  equal  in  productivity.  The  continuous-corn 
plot  still  enjoys  the  advantage  of  growing  the  crop  of  highest  money 
value  every  year,  but  in  spite  of  this  advantage  it  has  dropped  to  the 
lowest  position  in  financial  returns  because  of  the  more  rapid  decline  in 
yielding  power  under  this  system  of  farming.  At  the  close  of  the  period 
(1926)  the  average  annual  crop  values  are  $3.48  lower  than  for  the 
two-year  rotation.  The  three-year  rotation,  which  stood  higher  than 
the  two-year  at  the  beginning  of  the  experiment,  has  increased  its  lead. 

These  curves  (Fig.  3)  furnish  one  answer  to  the  question,  What 
are  the  objections  to  a  two-  or  three-year  rotation  without  fertiliza- 
tion? Without  fertilization  these  rotations  check  but  do  not  prevent 
declining  production.  In  thirty-nine  years  the  annual  value  of  the 
crop  from  the  plot  growing  corn  continuously  has  declined  from  $31.81 
an  acre  to  $14.33,  or  $17.48.  In  the  same  time  production  in  the  two- 
year  rotation  has  declined  from  $28.07  to  $17.81,  or  $10.26,  while  in 
the  three-year  rotation  there  has  been  a  reduction  from  $30.76  to 
$25.44,  amounting  to  $5.32.  If  these  trends  continue,  the  land  must 
eventually  become  unprofitable. 

Figs.  4,  5,  and  6,  illustrating  the  effect  of  the  manure,  limestone, 
phosphate  treatment  in  the  three  rotations,  all  tell  the  same  story. 
In  all  three  cropping  systems  the  treatment  used,  as  compared  with 
no  treatment,  has  maintained  production  at  a  significantly  higher  level 
and  has  converted  a  downward  trend  in  production  into  an  upward 
trend. 


$60 


.    920SZ 


-  5o</  untreated  Soil  treated 

Corn  75 1  Qatl  45*  Hay  f  15 


FIG.  4. — ANNUAL  CROP  VALUES  AND  TRENDS  FROM  LAND  CONTINUOUSLY 

IN  CORN,  MORROW  PLOTS 

On   continuous-corn    land,    manure,    limestone,   and    phosphate   convert    a 
downward  trend  in  production  into  an  upward  trend. 


1927] 


LESSONS  FROM  THE  MORROW  PLOTS 


119 


t     >. 


Soil  untreated  5oil  treated 

Corn    Jit  Oats  45*  flay  $15 


FIG.  5. — ANNUAL  CROP  VALUES  AND  TRENDS  IN  THE  CORN,  OATS 

ROTATION  OF  THE  MORROW  PLOTS 

Yields  from  the  treated  land  in  this  rotation  have  exceeded  those-  from  the 
untreated  land  every  year  but  two  for  nearly  a  quarter  of  a  century.  The  two 
adverse  years,  1905  and  1913,  indicate  how  misleading  a  single  year's  results 
may  be  as  a  test  of  a  soil  practice.  , 


960 


925.76 


-  Soil  untreated 
Corn    75* 


Jo//  treated 

Oats  45*  riay  tl5 


FIG.  6. — ANNUAL  CROP  VALUES  AND  TRENDS  IN  THE  CORN,  OATS, 

CLOVER  ROTATION  OF  THE  MORROW  PLOTS 

Even  in  this,  the  best  of  the  three  cropping  systems,  the  fertilization  scheme 
used  has  reversed  the  direction  of  the  production  trend,  carrying  it  consistently 
upward. 


120  BULLETIN  No.  300  [December, 

The  gap  in  the  production  trend  lines  between  the  treated  and  the 
untreated  land  is  about  the  same  in  all  three  cropping  systems  for  the 
beginning  of  the  period  of  soil  treatment  (1904).  The  widening  of 
this  gap  by  soil  treatment  has  been  greatest  in  the  two-year  rotation, 
where  it  amounts  to  $19.21  at  the  end  of  the  period,  and  is  narrowest 
on  the  continuous-corn  plot,  namely,  $16.52.  Thus  while  the  treatment 
used  has  not  produced  widely  different  results  in  the  three  cropping 
systems,  the  effect  of  soil  treatment  as  compared  to  no  soil  treatment 
has  been  very  marked  in  each  of  them. 

Soil  Treatment  and  Crop  Rotation  Hasten 
Maturity  of  Crops 

The  maturity  of  corn,  one  of  the  indexes  of  its  quality,  is  indi- 
cated largely  by  the  moisture  content  at  husking  time.  The  record 
of  the  moisture  content  of  corn  from  the  Morrow  plots  given  in  Table 
4  would  indicate  that  the  rotations  as  well  as  the  soil  treatment  tend  to 
hasten  the  maturing  of  corn. 

The  effect  of  the  soil  treatment  and  of  the  cropping  systems  in 
advancing  the  development  of  the  crop  is  shown  in  the  accompanying 
pictures.  These  photographs  were  taken  on  July  26,  1925.  On  that 
date  no  tassels  had  appeared  on  the  untreated  portion  of  Plot  3  (Fig. 
7)  and  only  an  occasional  tassel  was  to  be  seen  on  the  treated  portion. 
The  size  of  the  corn,  however,  was  noticeably  increased  where  soil 


FIG.  7. — THE  CORN  CROP  ON  THE  CONTINUOUS-CORN  PLOT  AS  IT 

APPEARED  JULY  26,  1925 

The  crop  is  further  along  on  the  treated  plot  than  where  no  soil  treatment 
has  been  applied.  On  August  4  the  treated  plot  was  fully  tasseled,  while  the  un- 
treated plot  was  only  partially  tasseled  out.  The  occasional  large  stalk  in  the 
foreground  of  the  untreated  plot  is  explained  by  the  fact  that  the  front  hill  in 
each  row  is  a  border  hill,  not  a  part  of  the  plot  proper.  Since  these  border  hills 
have  less  competition  with  surrounding  plants,  the  growth  is  much  larger  than 
that  in  the  plot  itself. 


1927] 


LESSONS  FROM  THE  MORROW  PLOTS 


121 


FIG.  8. — CORN  IN  THE  Two- YEAR  ROTATION  JULY  26,  1925 
The  stage  of  development  of  this  corn,  as  with  that  on  the  continuous-corn 
land,  is  advanced  by  the  use  of  manure,  limestone,  and  phosphate.     On  the 
treated  plots  the  tasseling  was  well  started  at  this  time,  while  very  few  tassels 
were  in  evidence  on  the  untreated  land. 


treatment  has  been  followed.  The  greatest  advance  in  growth  and  in 
earliness  of  tasseling  is  to  be  observed  on  the  treated  portion  of  the 
rotation  plots  (Figs.  8  and  9).  It  is  evident  both  from  the  pictures 
and  from  the  results  given  in  Table  4  that  the  soil  treatment  has  had  a 
more  pronounced  effect  in  advancing  the  crop  toward  maturity  than 
have  the  rotations. 


FIG.  9. — CORN  IN  THE  THREE- YEAR  ROTATION  JULY  26,  1925 
The  effect  of  soil  treatment  in  advancing  maturity  is  evidenced  here  as  in 
the  other  cropping  systems  shown  in  Figs.  7  and  8.   The  favorable  effect  of  the 
three-year  rotation  may  also  be  noticed  by  comparing  the  untreated  land  of  this 
plot  with  that  of  Plot  3,  Fig.  7. 


122 


BULLETIN  No.  300 


[December, 


TABLE  4. — EFFECT  OF  SOIL  TREATMENT  AND  OF  CROP  ROTATION  ON  MOISTURE 
CONTENT  OF  CORN,  MORROW  PLOTS,  AVERAGE  1909-1926 


Rotation 

Percentage  of  water-free 
shelled  corn  from  ear 
corn  at  husking  time 

Field  weight  of  ear  corn  to 
make  1  bushel  of  No.  1 
shelled  corn1 

Continuous  corn 
No  treatment  

percent 
57.8 

Ibs. 
86.3 

MLP          

60.1 

83.4 

Corn,  oats 

58.8 

85.2 

MLP   

61.4 

81.4 

Corn,  oats,  clover 
No  treatment  

59.2 

84.5 

MLP  

61.1 

82.0 

'Based  upon  12  percent  moisture. 


EFFECTS  OF  ROTATION  AND  FERTILIZATION  ON  THE  SOIL 

The  cropping  system  practiced  on  a  soil  and  the  fertilization  used 
may  affect  not  only  the  crops  grown,  but  also  the  physical  condition, 
the.  biological  activities,  and  the  chemical  character  of  the  soil  itself. 
The  following  investigations  were  undertaken  in  order  to  study  certain 
chemical  and  biological  aspects  of  the  soil  of  the  various  plots.  For 
this  purpose,  soil  samples  were  used  which  had  been  collected  in  1913 
and  1923,  together  with  a  less  complete  set  taken  in  1904.  The  samples 
were  taken  from  three  strata  in  each  plot,  an  upper  or  surface  stratum 
extending  to  a  depth  of  6%  inches,  a  middle  stratum  extending  from 
6%  to  20  inches,  and  a  lower  stratum,  extending  from  20  to  40  inches. 
The  upper  stratum  corresponds  approximately  to  2  million  pounds  an 
acre  of  dry  soil.  The  middle  and  lower  strata  represent,  respectively, 
two  and  three  times  this  amount,  and  the  results  of  analyses  are  com- 
puted to  pounds  per  acre  on  this  basis.  Most  of  the  feeding  roots  of  our 
common  crop  plants  are  distributed  within  the  upper  20  inches  of  soil, 
altho  some  roots  of  all  these  plants  extend  to  a  depth  of  40  inches  or 
more.  Thus  while  the  upper  stratum,  with  which  the  manure  and  fer- 
tilizing materials  are  incorporated,  constitutes  the  most  important  feed- 
ing zone  and  the  second  stratum  is  one  of  secondary  importance,  it  must 
be  considered  that  the  entire  40  inches  may  possibly  be  drawn  upon 
by  crops  to  some  extent.  Since,  however,  differences  brought  about 
by  cropping  or  fertilization  that  are  great  enough  to  be  discernible 
by  chemical  methods,  are  found  mainly  in  the  upper  stratum,  and  only 
to  a  very  slight  extent  in  the  second,  the  data  presented  and  the  dis- 
cussion will  be  confined  to  these  two  strata,  even  tho  the  chemical  in- 
vestigations have  been  made  on  the  lower  stratum  as  well. 

Decline  in  Nitrogen  and  Organic  Matter 
Prevented  by  Soil  Treatment 

The  soil  on  which  the  Morrow  plots  are  located  is  fairly  well 
supplied  with  nitrogen  and  organic  matter.  The  untreated  soil  to  a 


1927] 


LESSONS  FROM  THE  MORROW  PLOTS 


123 


depth  of  6%  inches  contains  approximately  45,000  pounds  of  organic 
carbon1  to  the  acre.  The  organic  matter  continues  to  a  considerable 
depth.  The  second  stratum,  6%  to  20  inches,  which  is  twice  as  thick 
as  the  upper  one,  contains  nearly  80,000  pounds  of  organic  carbon 
to  the  acre,  a  slightly  lower  concentration  than  is  found  in  the  sur- 
face soil.  Nitrogen  is  associated  with  the  organic  matter,  most  soil 
nitrogen  being  in  the  organic  form. 

Since  both  nitrogen  and  organic  matter  are  fairly  high  in  this  soil, 
it  is  not  necessary  that  they  be  actually  increased  in  order  to  maintain 
a  high  level  of  production ;  it  is  necessary,  however,  to  keep  the  quan- 
tities of  these  important  soil  constituents  at  somewhere  near  their 
original  level. 


No  treatment 


Manure,  limestone,  phosphate 


4OOO    — 


1913  IS23 

Continuous    Corn 


19/3          1923 
Corn,oatj  rotation 


1913         '923 
Corn,oats,clOver  rotation 


FIG.  10. — TOTAL  NITROGEN  IN  SURFACE  SOIL  OF  THE  MORROW 

PLOTS,  1913  AND  1923 

The  use  of  limestone,  manure,  and  phosphate  has  in  all  cases  maintained 
the  quantity  of  total  nitrogen  in  this  stratum  (0  to  6%  inches)  at  a  slightly 
higher  level  than  where  no  treatment  has  been  applied.  In  this  respect  the  rota- 
tions show  some  advantage  over  continuous  cropping  to  corn.  It  will  be  noted 
also  that  the  treated  plots  all  contained  more  nitrogen  in  1923  than  the  untreated 
plots  contained  at  the  beginning  of  the  ten-year  period. 


The  results  of  analyses  for  nitrogen  presented  in  Figs.  10  and  11 
show  that  during  the  ten  years  from  1913  to  1923  there  was  no  great 
change  in  the  total  amount  of  this  element  to  a  depth  of  20  inches. 
The  decreases  in  the  untreated  soil  averaged  approximately  90  pounds 
an  acre  a  year  for  the  entire  20-inch  stratum.  While  this  amount  is 
but  little  more  than  could  be  accounted  for  by  unavoidable  errors  in 
collecting  two  different  sets  of  samples  at  different  times,  it  is  clear 
that  it  is  not  wholly  due  to  such  errors,  since  in  both  the  surface  and 
subsurface  of  every  untreated  plot  the  variation  is  consistently  a  de- 
crease, even  tho  slight.  It  would  appear  then  that  there  has  been  a 


'Organic  carbon  constitutes  approximately  58  percent  of  the  organic  matter 
and  is  used  as  a  measure  of  the  organic  matter  in  the  soil. 


124 


BULLETIN  No.  300 


[December, 


definite  reduction  in  the  amount  of  nitrogen  in  the  soil  of  the  un- 
treated plots.  In  the  treated  plots  the  applications  of  manure,  lime- 
stone, and  phosphate  have  prevented  this  decrease  in  the  total  nitrogen 
content  of  the  soil.  All  these  plots  at  the  present  time  contain  not 


Manure,  limestone,  phosphate 


1913          I9Z3 

Continuous   corn 


1913          1923  /9/3          /923 

Corn,  oafj  rotation      Corn. oats,  clover  rotation 


FIG.  11. — TOTAL  NITROGEN  IN  SUBSURFACE  SOIL  OF  THE  MORROW 

PLOTS,  1913  AND  1923 

The  greater  quantities  of  total  nitrogen  in  the  second  stratum  (6%  to  20 
inches)  of  the  treated  plots  as  compared  with  the  untreated  plots  indicate  that 
these  treatments  have  been  effective  below  the  6%-inch  level. 


only  more  nitrogen  than  the  corresponding  untreated  plots,  but  more 
than  those  untreated  plots 'contained  at  the  beginning  of  the  ten-year 
period.  These  differences  again  are  not  large,  but  their  consistency 
lends  weight  to  their  significance. 

That  these  small  but  consistent  differences  are  significant  is  indi- 
cated by  computing  the  odds  by  means  of  a  statistical  method.1 
The  odds  that  the  decrease  of  90  pounds  of  nitrogen  annually  is  sig- 
nificant are  5,000  to  1.  The  increases  in  the  treated  soil  are  significant 
by  odds  of  over  3,000  to  1,  while  the  increases  in  the  treated  soil  as 
compared  to  the  untreated  soil  at  the  beginning  of  the  ten-year  interval 
are  backed  by  odds  of  76  to  1. 

The  organic-matter  content  of  the  soil  of  the  plots  has  been 
affected  in  much  the  same  way  as  the  nitrogen  content  (Figs.  12  and 
13). 

It  will  be  noted  that  the  organic  carbon  and  nitrogen  tend  to  be 
higher  in  the  soil  of  the  plots  where  the  two-  and  three-year  rotations 
are  grown  than  where  corn  has  been  grown  continuously.  Since  no 
soil  samples  were  taken  when  these  plots  were  established,  there  is 
no  way  of  determining  with  certainty  whether  this  is  a  result  of  the 


'Student's  Method.  H.  H.  Love,  in  Jour.  Amer.  Soc.  of  Agron.  16,  68.  1924. 


1927] 


LESSONS  FROM  THE  MORROW  PLOTS 


125 


Ato  treatment    VA  Manure,  limestone,  phosphate 


I9Z3 


1913 


Continuous    corn       Corn,  oats  rotation   Corn, oats,cloyer  rotation 

FIG.  12. — ORGANIC  CARBON  IN. SURFACE  SOIL  OF  THE  MORROW 

PLOTS,  1913  AND  1923 

Total  nitrogen  and  organic  carbon  are  associated  in  a  fairly  constant  ratio 
in  the  organic  matter  of  the  soil.  Consequently  the  variations  here  shown  in 
organic  carbon  parallel  those  for  total  nitrogen  shown  in  Fig.  10.  The  treated 
plots  are  seen  to  be  somewhat  better  supplied  than  the  untreated  plots  with  this 
element,  and  the  rotations  show  some  advantage  over  continuous  corn. 

crop  rotations  or  whether  the  soil  was  naturally  richer  in  these  ele- 
ments toward  the  south  end  of  the  field  in  the  beginning. 

While  the  foregoing  data  do  not  prove  conclusively  that  the  crop- 
ping systems  have  greatly  affected  the  amount  of  organic  matter  in  the 
soil  at  the  present  time,  the  results  presented  in  the  following  section 
do  afford  evidence  of  the  effect  of  both  cropping  systems  and  soil 
treatment  upon  the  quality  of  the  organic  matter.  That  is  to  say,  these 
cropping  systems  and  soil  treatments  have  periodically  added  to  the 
comparatively  inactive  organic  matter  already  in  the  soil  varying  quan- 
tities of  active  organic  matter  which,  because  of  its  susceptibility  to 
decomposition,  has  an  enhanced  value  in  maintaining  conditions  favor- 
able to  high  production. 


\No  Treatment 


Manure,  limestone,  phosphate 


19/3  1923  '9/3  I9Z3  1913          1923 

Continuous  corn       Corn,  oats  rotation  Corn.oafc,  clover  rotation 

FIG.  13. — ORGANIC  CARBON  IN  SUBSURFACE  SOIL  OF  THE  MORROW 

PLOTS,  1913  AND  1923 

As  in  the  case  of  nitrogen,  the  influence  of  the  soil  treatments  and  crop 
rotations  on  the  organic  matter  reaches  below  the  6%-inch  level. 


126  BULLETIN  No.  300  [December, 

Biological  Activity  Increased  by  Better  Practices 
Organic  matter  in  the  soil  is  of  greatest  value  when  it  is  under- 
going decay.  This  process  is  brought  about  by  bacteria  and  other 
microscopic  organisms.  The  rate  at  which  it  proceeds  depends  largely 
upon  the  age,  condition,  and  origin  of  the  organic  matter,  and  also 
upon  the  existence  in  the  soil  of  conditions  favorable  to  the  growth 
of  the  organisms  which  cause  decay.  Much  of  the  organic  matter  in 
the  soil  consists  of  old  plant  residues  which  have  accumulated  thru 
the  centuries  because  of  their  resistance  to  decay,  and  20  tons  of  such 
old  inactive  organic  matter  may  be  of  less  benefit  to  a  crop  than  2 
tons  of  clover  or  cowpeas  freshly  plowed  under. 

The  biological  activity  in  a  soil,  which  is  a  reflection  of  the  quality 
of  the  organic  matter,  may  be  effectively  measured  by  determining 
the  rate  at  which  nitrogen  in  the  soil  is  converted  by  soil  bacteria 
into  the  nitrate  form  and  thus  made  available  for  use  by  crops.  This 
has  been  done  in  the  laboratory1  with  soil  taken  from  the  Morrow 

?* 

**  ^f  P77I 

«•  J  •  A/o  treatment  uA  Manure,  limestone,  phosphate 

^.  ^  too  — 

£  o   S°~ 

\* 


Continuous  corn  Cornt  oats,  clover  rotation 


FIG.   14. — NITROGEN  CONVERTED  INTO  NITRATE  IN  FOUR  WEEKS,  IN 

SAMPLES  OF  SOIL  TAKEN  FROM  THE  MORROW  PLOTS  IN  1923 
Even  the  comparatively  resistant  nitrogen  of  the  soil  is  made  available 
more  rapidly  under  conditions  brought  about  by  good  management  than  where 
rotations  and  soil  treatment  are  ignored.  The  nitrogen  converted  to  nitrate  in 
the  soil  of  the  three-year  rotation  under  treatment  would  be  sufficient  to  produce 
more  than  twice  the  crop  possible  in  the  case  of  the  untreated,  continuous-corn 
plot.  As  a  matter  of  fact,  the  yields  from'  these  plots  have  been  in  very  nearly 
that  ratio. 

plots  in  1923,  after  forty-seven  years  of  cropping,  and  in  the  case  of 
the  treated  plots,  after  nineteen  years  of  fertilization. 

The  amounts  of  nitrogen  converted  into  nitrate  in  four  weeks 
from  the  soil  organic  matter  alone  are  shown  in  Fig.  14.  When  it  is 
considered  that  approximately  1%  pounds  of  nitrate  nitrogen  are  re- 
quired to  grow  a  bushel  of  corn,  the  significance  of  these  results  is 
at  once  apparent.  The  91  pounds  of  nitrogen  converted  to  nitrate  in 
the  soil  growing  the  three-year  rotation  under  treatment  would  pro- 
duce more  than  twice  the  crop  possible  in  the  case  of  the  untreated 
continuous-corn  plot,  where  but  43  pounds  an  acre  was  thus  liberated. 
Indeed,  the  amounts  of  nitrogen  liberated  from  the  soil  of  the  differ- 

'The  authors  are  indebted  to  Professor  O.  H.  Sears  for  the  nitrification  de- 
terminations. 


1927] 


127 


ent  plots  stand  in  very  nearly  the  same  ratio  as  the  actual  average 
crop  yields  from  those  plots  during  the  last  twenty-three  years. 

The  results  of  a  similar  study  are  given  in  Fig.  15,  the  only  dif- 
ference being  that  ammonium  sulfate  was  added  in  equal  amounts 
to  all  the  soil  samples  at  the  beginning  of  the  four-week  period.  This 
material  furnishes  an  abundant  supply  of  nitrogen  which  is  capable  of 
being  converted  into  the  nitrate  form  more  readily  than  soil  nitrogen. 
The  results  here  are  even  more  striking.  Both  rotation  and  fertiliza- 
tion are  shown  to  keep  the  soil  in  much  more  favorable  condition  for 
the  growth  of  these  beneficial  bacteria  than  is  the  case  where  these 
practices  are  not  followed. 

Thus  while  the  better  practices  in  soil  management  have  not 
caused  the  accumulation  of  a  large  excess  of  organic  matter  which 

I  A/o  Treafment     ^  Manure,  limestone,  phosphate 


nitrate- 
surface 

zoo  — 

I 

«o^ 

too   — 

fef 

11 

J 

^ 

Continuous    corn      Corn,  oats  rotation    Corn,  oats,  clover  rotation 

FIG.  15. — NITRATE  NITROGEN  FORMED  IN  FOUR  WEEKS  IN  SAMPLES  OF  SOIL 
TAKEN  FROM  THE  MORROW  PLOTS  IN  1923  AND  TREATED  WITH 

AMMONIUM  SULFATE 

The  relative  ability  of  different  soils  to  convert  unavailable  nitrogen  into 
available  form  (nitrate)  is  readily  measured  in  the  laboratory  by  determining 
the  rate  of  nitrate  formation  from  equal  amounts  of  ammonium  sulfate.  As  is 
shown  in  this  graph,  the  amount  of  nitrate  nitrogen  thus  formed  is  very  greatly 
enhanced  in  the  soil  carrying  good  rotations  and  in  that  which  has  received  the 
manure,  limestone,  phosphate  treatment. 


may  be  demonstrated  by  soil  analysis,  they  nevertheless  have  added 
significantly  greater  amounts  of  active  organic  materials  than  the 
poorer  practices.  The  growth  of  plant  parts,  such  as  stubble,  roots, 
and  clover  sod,  is  greater,  and  the  manure  applied  to  the  treated  plots 
has  amounted  to  about  3  tons  an  acre  yearly.  This  excess  organic 
matter,  produced  thruout  the  entire  period,  has  been  largely  decom- 
posed year  by  year  for  the  benefit  of  the  crops  grown  and  therefore 
does  not  appear  in  the  final  analysis  of  the  soil. 

The  benefit  from  the  increased  amount  of  active  organic  matter 
consists  not  solely  in  the  increased  liberation  of  nitrogen;  it  makes 
possible  also  the  liberation  from  soil  minerals  of  other  elements  used 
by  crops,  such  as  phosphorus,  calcium,  and  potassium. 


128 


BULLETIN  No.  300 


[December, 


Phosphorus  Depletion  Offset  by  Phosphates  and  Manure 

Soil  phosphorus  is  removed  by  cropping.  The  corn  on  the  un- 
treated continuous-corn  plot  has  removed  phosphorus  at  the  rate  of 
approximately  6  pounds  an  acre  a  year,  or  a  total  of  60  pounds  an 
acre  during  the  ten  years  from  1913  to  1923  if  we  use  as  a  basis  for 
our  figures  the  actual  crop  yields  and  the  average  composition  of 
corn.  This  is  the  smallest  amount  of  phosphorus  removed  from  any 
of  the  plots.  Figured  on  the  same  basis,  the  largest  amount  removed 
from  any  one  plot  has  been  from  the  treated  plot  carrying  the  three- 
year  rotation  (Plot  5-S).  The  corn,  oats,  and  clover  harvested  from 
this  plot  have  taken  from  the  soil  about  136  pounds  of  phosphorus  an 
acre  during  the  ten-year  period.  Most  of  this  has  probably  been  taken 


.c 


'O4  '13    '23 

No  treatment 


'13  '23 

Limestone,  manure, 
bone  meal 


'04  'IS    '25 

Limestone,  manure, 
rocH  phosphate 


FIG.  16. — TOTAL  PHOSPHORUS  IN  SURFACE  SOIL  OF  THE  MORROW  PLOTS  IN 

CONTINUOUS  CORN  :  1904,  1913,  1923 

The  gradual  reduction  of  soil  phosphorus  by  cropping  is  easily  offset  by 
the  application  of  phosphate  fertilizers.  It  is  interesting  to  note  that  the  phos- 
phorus content  of  the  soil  has  just  about  been  maintained  by  the  bone-meal 
applications,  while  the  larger  amounts  of  rock  phosphate  used  have  practically 
doubled  the  phosphorus  reserve  in  the  surface  soil. 


from  the  upper  6%  inches  of  soil,  but  some  has  been  obtained  from 
the  second  stratum  and  perhaps  from  still  deeper  layers.  Since  dupli- 
cate chemical  determinations  of  phosphorus  on  the  same  soil  sample 
will  vary  on  the  average  from  50  to  75  pounds  in  the  surface  soil  of 
one  acre,  this  reduction  in  phosphorus  content  in  the  Morrow  plots 
due  to  crop  removals  obviously  could  not  be  determined  with  certainty 
by  chemical  analyses  of  the  soil  made  at  the  beginning  and  end  of  a 
ten-year  period. 

On  all  treated  plots  phosphorus  has  been  added,  not  only  in  bone 
meal  and  phosphate  rock,  but  also  in  manure,  which  has  been  the 
means  of  returning  to  the  soil  more  than  half  of  the  phosphorus  re- 


1927] 


LESSONS  FROM  THE  MORROW  PLOTS 


129 


moved  by  the  crops  harvested  and  fed.  Fig.  16  gives  the  phosphorus 
content  of  the  surface  soil  of  the  continuous-corn  plots  as  found  by 
analysis,  showing  separately  the  untreated  plot  and  the  plots  treated 
with  bone  meal  and  with  rock  phosphate.  The  results  of  an  earlier 
analysis  in  1904,  just  before  the  treatments  were  started,  are  inserted 
for  comparison. 

The  plots  on  which  rock  phosphate  has  been  applied  show  a  much 
greater  increase  in  phosphorus  content  than  those  on  which  bone  meal 
has  been  applied.  It  will  be  remembered  that  rock  phosphate,  which 
contains  approximately  the  same  percentage  of  phosphorus  as  bone 
meal,  has  been  applied  in  four  times  as  great  amounts  as  the  bone. 
The  results  in  the  rotation  plots,  which'  are  not  presented  here,  are 
very  similar  to  those  given  for  the  plot  growing  corn  continuously. 


u  fj 

No  treatment 


'13    '23 

Limestone,  manure, 
bone  meal 


13    23 

Limestone,  manure, 
rock  phosphate 


FIG.  17. — I'OTAL  PHOSPHORUS  IN  SUBSURFACE  SOIL  OF  THE  MORROW  PLOTS 

IN  CONTINUOUS  CORN  :  1913,  1923 

The  influence  of  phosphate  applications  to  the  soil  is  largely  limited  to  the 
surface  stratum. 

It  should  be  noted  also  that  the  treatments  used  have  had  no 
observable  effect  upon  the  phosphorus  content  of  the  soil  below  the 
surface  (Fig.  17). 

While  cropping  makes  relatively  slight  inroads  upon  the  total 
amount  of  phosphorus  in  the  soil,  it  draws  heavily  upon  that  por- 
tion which  readily  becomes  soluble,  as  in  the  case  of  nitrogen.  This 
is  an  important  fact  reflected  in  the  trend  of  crop  yields.  The  re- 
moval year  after  year  of  the  more  available  fraction  of  the  soil  phos- 
phorus leaves  a  residue  from  which  it  becomes  increasingly  difficult 
for  succeeding  crops  to  extract  the  amount  required  for  their  growth. 
This  difficulty  may  be  overcome  in  part  by  renewing  the  supply  of 
active  organic  matter  in  the  soil,  so  that  biological  activity  will  be 
maintained  and  will  aid  in  the  liberation  of  this  element,  as  discussed 
earlier  (pages  126  and  127).  Two  additional  methods  of  remedying 
the  situation  are  possible,  both  of  which  are  used  on  the  Morrow  plots. 
One  is  to  apply  relatively  available  phosphates,  such  as  bone  meal  or 


130  BULLETIN  No.  300  [December, 

acid  phosphate,  from  time  to  time  in  amounts  commensurate  with  crop 
removals.  The  other  is  to  use  a  comparatively  insoluble  phosphate, 
rock  phosphate  for  example,  in  much  larger  quantities,  under  the  as- 
sumption that  the  small  percentage  of  it  becoming  available  each  year 
will  fulfill  crop  requirements. 


Calcium,  Magnesium,  and  Sulfur 

No  pronounced  differences  are  to  be  found  in  the  total  amounts 
of  calcium,  magnesium,  or  sulfur  in  the  various  plots  due  to  either 
cropping  or  fertilization,  with  the  exception  of  a  gain  in  calcium  in 
the  surface  soil  of  the  treated  plots,  where  calcium  has  been  added  in 
both  the  limestone  and  the  phosphates  applied. 

What  has  been  said  of  phosphorus  is  equally  true  of  these  other 
minerals,  namely,  that  as  continuous  cropping,  with  the  accompanying 
gradual  soil  exhaustion,  proceeds,  it  is  that  portion  which  can  readily 
become  available  which  suffers  the  most  complete  removal  by  crops. 
An  interesting  side  light  on  this  situation  is  shown  in  the  "come-back" 
which  soils  undergoing  gradual  exhaustion  sometimes  exhibit  in  the 
year  following  a  bad  season.  For  example,  in  1916,  a  poor  corn  year, 
Plot  3-N  yielded  11.2  bushels  of  corn  (Table  2),  followed  in  the  next 
year  by  a  yield  of  40  bushels.  It  is  conceivable  that  the  high  yield  in 
1917  was  due,  not  wholly  to  the  more  favorable  weather  conditions, 
but  also  in  part  to  the  light  drain  upon  the  available  nutrient  elements 
by  the  small  crop  of  1916,  which  permitted  some  accumulation. 

Soil  Acidity  Neutralized  by  Limestone 

Chemical  tests  show  that  the  surface  soil  of  all  of  the  untreated 
plots  is  distinctly  acid,  while  on  the  treated  plots  the  acidity  has  been 
almost  completely  neutralized  by  the  moderate  amount  of  limestone 
used.  The  untreated  soil  has  not  yet  become  so  acid  as  to  prevent  the 
growth  of  red  clover,  satisfactory  stands  being  maintained  both  on 
Plot  5-N  and  5-S,  but  it  has  become  too  acid  to  grow  sweet  clover. 
This  was  shown  by  an  accidental  seeding  of  sweet  clover  in  the  oats 
on  Plots  5-N  and  5-S  in  1923  in  addition  to  the  red  clover.  In  the  fol- 
lowing year  sweet  clover  grew  abundantly  on  the  limed  plot,  almost 
crowding  out  the  red  clover  and  producing  a  yield  of  4.42  tons  of  hay, 
while  on  the  untreated  plot  there  was  a  good  growth  of  red  clover, 
yielding  1.83  tons  an  acre  of  hay,  but  no  sweet  clover.  The  handicap 
of  even  a  moderately  acid  soil  is  evident  from  an  observation  of  Plots 
4-S  and  4-N  in  the  years  when  these  plots  are  in  oats.  An  abundant 
growth  of  sweet  clover  is  to  be  seen  on  the  former,  which  has  been 
limed,  while  on  the  latter,  which  is  still  acid,  only  a  light  covering  of 
grasses  and  small  weeds  will  be  seen. 


1927] 


LESSONS  FROM  THE  MORROW  PLOTS 
ECONOMIC   LESSONS  FROM   THE  PLOTS 


131 


The  foregoing  analysis  has  been  concerned  only  with  the  ques- 
tions of  soil  maintenance  and  crop  yields.  A  question  of  equal  im- 
portance is :  What  is  the  relative  profitableness  of  the  different  crop- 
ping and  fertilization  practices  used  on  the  Morrow  plots  ?  The  farmer 
is  particularly  concerned  with  this  question,  and  while  the  answer  may 
be  determined  to  a  considerable  extent  by  factors  which  can  be  meas- 
ured in  plot  experiments,  it  must  be  remembered  that  the  results 

TABLE  5. — COST  OF  PRODUCING  THE  CROPS  GROWN  ON  THE  MORROW  PLOTS, 

1904-1926 

(Based  on  production  costs  secured  in  cost-accounting  investigations  carried  on  by  the  Department 

of  Farm  Organization  and  Management  of  the  University  of  Illinois,  in 

Champaign  and  Piatt  counties) 


Plot3 

Plot  4 

Plots 

Corn 

Corn 

Oats 

Corn 

Oats 

Clover 

Yearly  cost  per  acre  without  soil  treatment 


Average  yield  per  acre  

25.1  bu. 

35.6bu. 

34.0bu. 

SO.Obu. 

45.1  bu. 

1  .  39  tons 

Costs  that  are  the  same  re- 
gardless of  the  crop 
Interest  and  taxes  on  land1 
General  tillage  machinery 
and  hitches  

$11.83 

.72 

$11.83 

.72 

$11.83 

.72 

$11.83 

.72 

$11.83 

.72 

$11.83 

.72 

Costs  that  vary  with  different 
crops  and  with  varying 
yields 

Man  labor 
(a)  harvesting  and 
threshing  

.84 

1.26 

.17 

1.73 

.22 

1.33 

(b)  other  

2.23 

2.23 

1.37 

2.23 

1.37 

.66 

Horse  labor 
(a)  harvesting  and 
threshing  

1.22 

1.83 

1.26 

2.45 

1.34 

1.26 

(b)  other 

4.68 

4.68 

1.40 

4.68 

1  40 

1.21 

Seed  

.39 

.39 

.84 

.39 

.84 

2.64 

Twine  

.30 

.33 

Fuel  

.10 

.11 

Threshing 

.88 

1.17 

General  farm  expense  
Crop  machinery  

2.80 
.45 

3.12 
.50 

1.80 
.54 

3.36 
.54 

2.24 
.61 

1.95 
.68 

Total  cost  of  each  crop  per 
acre  .            .    . 

$25.16 

$26.56 

$21.21 

$27.93 

$22.18 

$22.28 

Annual  cost  of  producing  an 
acre  of  rotation  

$25.16 

$23. 

89 

$24.13 

Cost  with  soil  treatment 


Increase  in  yield 

15  4  bu. 

23  6  bu. 

24.  1  bu. 

16.6bu.       17.6bu. 

1.01  tons 

Cost  of  limestone,  phosphate, 
and  manure2 

$  5  78 

$  5. 

75 

$  5.59 

Cost  of  harvesting  increased 
crop  

1  39 

1. 

83 

1.94 

Production  costs  without  soil 
treatment  

25.16 

23 

.89 

24.13 

Total  annual  cost  of  produc- 
ing an  acre  of  rotation.  .  .  . 

$32.33 

$31 

.47 

$31.66 

'Land  valued  at  $200  an  acre;  interest  at  5  percent. 

>Manure  at  75  cents  a  ton;  limestone  and  phosphate  as  on  pages  110  and  111.     Cost  of  applying  is 
not  included. 


132 


BULLETIN  No.  300 


[December, 


TABLE  6. — ANNUAL  NET  RETURN  PER  ACRE  OF  ROTATION  WITH  AND  WITHOUT 
SOIL  TREATMENT,  MORROW  PLOTS,  1904-1926 

(Corn  valued  at  75  cents  a  bushel,  oats  at  45  cents  a  bushel,  and  clover  hay  at  $15  a  ton.    These  ap- 
proximate the  average  prices  for  the  last  ten  years) 


Plot3 

Plot  4 

PlotS 

Without 
soil 
treatment 

With 
soil 
treatment 

Without 
soil 
treatment 

With 
soil 
treatment 

Without 
soil 
treatment 

With 
soil 
treatment 

25.1  bu. 

40.5  bu. 

35.6bu. 
34.0  bu. 

59.2  bu. 
58.1  bu. 

SO.Obu. 
45.1  bu. 
1.39T 

66.6bu. 
62.7  bu. 
2.40T 

Average  oats  yield  

Average  clover  yield  

Annual  crop  value  per  acre  of 

$18.83 
25.16 

$30.38 
32.33 

$21.00 
23.89 

$35.28 
31.47 

$26.22 
24.13 

$38.06 
31.66 

Annual  cost  per  acre  of  rota- 
tion   

Annual  net  retujn  per  acre  of 

$-6.33 

$-1.95 

$-2.89 

$  3.81 

$  2.09 

$  6.40 

Annual  net  increase  due  to 
soil  treatment  

$4.38 

$6.70 

$4.31 

which  any  individual  farmer  will  achieve  will  depend  in  large  part 
upon  his  own  business  ability  and  thrift. 

A  satisfactory  method  for  determining  the  relative  profitableness 
or  unprofitableness  of  the  different  cropping  systems  used  on  the 
Morrow  plots  with  or  without  soil  treatment  is  to  deduct  from  the 
value  of  all  the  crops  produced  the  total  cost  of  growing  them.  In 
Table  6  are  shown  the  results  of  such  a  computation  for  each  of  the 
plots  from  1904  thru  1926,  the  cost  data1  being  taken  from  the  cost 
analysis  given  in  Table  5.  Table  7  contains  the  results  for  the  earlier 
years,  1888  thru  1903,  when  no  soil  treatment  was  given. 

An  inspection  of  Table  6  shows  that  the  continuous  growing  of 
corn  without  soil  treatment  has  resulted  in  a  loss,  as  a  long-time  prop- 
osition. Computed  for  the  earlier  years  alone,  1888  thru  1903  (Table 
7),  the  results  show  that  if  the  same  cost  and  price  conditions  had  pre- 
vailed, a  profit  would  have  been  realized  from  the  continuous  growing 
of  corn  during  that  period,  owing  to  the  high  initial  productiveness  of 
the  soil.  The  corn  and  oats  rotation  without  soil  treatment  was  main- 
tained without  loss  during  the  early  period.  The  average  annual  net 
profit,  however,  amounted  to  only  69  cents  an  acre,  and  this  cropping 
system  gradually  became  unprofitable  because  of  declining  yields.  Dur- 
ing the  last  twenty-three  years  a  net  annual  loss  of  $2.89  an  acre  has 
resulted. 


'The  figures  on  cost  of  production  used  in  the  tables  and  discussion  are 
based  on  data  secured  in  farm-accounting  investigations  which  have  been 
carried  on  by  the  Department  of  Farm  Organization  and  Management  of  the 
University  of  Illinois  in  Champaign  and  Piatt  counties,  since  it  would  be  impos- 
sible to  obtain  the  actual  cost  of  production  from  crops  grown  under  experi- 
mental conditions  on  plots  of  such  limited  size.  As  no  manager's  salary  has 
been  included  in  the  production  costs,  the  net  profits,  where  they  occur,  may  be 
considered  as  the  manager's  or  owner's  wage. 


1927] 


LESSONS  FROM  THE  MORROW  PLOTS 


133 


TABLE  7. — ANNUAL  NET  RETURN  PER  ACRE  OF  ROTATION  WITHOUT  SOIL  TREAT- 
MENT, MORROW  PLOTS,  1888-19031 


Plot  3 

Plot  4 

Plot  5 

Corn 

Corn 

Oats 

Corn 

Oats 

Clover 

Yield  per  acre                  .    .    . 

39.  7  bu. 
$26.41 

41.0  bo. 

$27.11 

44.0bu. 
$22.05 

tS.Otra. 

$27.83 

47.6bu. 
$22.35 

2.03T 
$23.29 

Annual  cost  of  each  crop  per 
acre  

Annual  crop  value  per  acre  of 

$29.77 
26.41 

$25.29 
24.58 

$29.29 
24.52 

Annual  cost  per  acre  of  the 
rotation  

Annual  net  return  per  acre  of 
rotation  

$  3.36 

$     .69 

$  4.77 

'Cost  data  taken  from  Table  6  and  corrected  for  differences  in  yield. 


The  greatest  net  profits  have  been  realized  from  the  two-  and 
three-year  rotations  in  which  manure,  limestone,  and  phosphate  have 
been  used.  '  The  annual  net  acre  profit  in  these  two  systems  from  1904 
thru  1926  has  averaged  $3.81  and  $6.40  respectively  (Table  6).  The 
plot  growing  corn  continuously  even  with  the  soil  treatment  shows  a 
loss  of  $1.95.  Any  variation  in  prices  of  farm  products  would  of 
course  change  these  results,  and  might  even  convert  small  net  profits 
into  losses,  or  vice  versa.  Changes  in  economic  conditions  affecting 
production  cost,  such  as  the  varying  costs  of  supplying  fertilizers, 
would  likewise  exert  their  effect  upon  the  absolute  profit  or  loss. 

One  factor  in  particular  merits  attention  in  this  discussion  of 
the  relative  profitableness  of  different  rotation  and  fertilization  prac- 
tices, because  of  the  marked  influence  which  it  exerts  upon  the  total 
cost  of  producing  crops.  This  is  the  distribution  of  labor  thruout  the 
year.  Fig.  18  illustrates  the  labor  distribution  on  a  typical  farm  in 
Champaign  county  which  is  devoted  to  the  growing  of  corn,  oats,  and 
clover.  It  will  be  observed  that  the  inclusion  in  the  rotation  of  either 
oats  or  clover,  or  both,  results  in  a  demand  for  labor  at  times  when 
the  labor  is  not  being  used  to  its  full  capacity  on  the  corn  crop.  Con- 
sequently a  given  acreage  in  a  two-  or  three-year  rotation,  such  as 
that  used  on  the  Morrow  plots,  could  be  handled  with  fewer  men  and 
work  horses  than  if  it  were  all  planted  to  corn;  also,  more  hours  of 
work  could  be  secured  per  man  and  per  horse,  and  at  a  lower  cost  per 
hour.  These  statements  should  not  be  construed  to  mean  that  the  two 
rotations  used  on  these  plots  are  ideal  or  that  they  are  to  be  recom- 
mended in  any  particular  case.  Other  rotations  could  be  devised  which 
might  fit  the  conditions  on  any  given  farm  better  than  these.  The  point 
is  that  diversification  of  crops  grown  in  rotation  does  bring  about  a 
more  economical  distribution  of  farm  labor  than  continuous  cropping 
to  the  same  crop. 

Variations  in  the  productive  power  of  land  are  certain  to  be  re- 
flected in  land  values.  In  computing  the  cost  of  production  to  be  de- 


134 


BULLETIN  No.  300 


[December, 


ducted  from  the  total  crop  value,  as  has  been  done  in  Tables  6  and  7, 
there  has  been  included  a  charge  of  5  percent  interest  on  the  value 
of  the  land,  which  is  placed  at  $200.  If,  however,  we  base  the  value 
of  the  land  on  what  it  will  produce,  we  have  a  vivid  picture  of  what 
declining  productiveness  means.  If  all  costs  except  the  land  charge  are 


/fot/rj  y'Peo/t  for    corn 


jan.     Feb.     Mar.     Apr.     May   June  July     Aug.  Sept.    Oct.      Nov.     Dec. 


FIG.  18. — DISTRIBUTION  OF  LABOR  THRU  THE  YEAR  BY  Two- WEEK  PERIODS 

ON  TYPICAL  CORN-BELT  FARMS 

The  height  of  the  bars  represents  the  number  of  man  hours  or  horse  hours 
an  acre  required  by  the  various  crops.  Diversification  of  crops  grown  in  rota- 
tion brings  about  a  more  economical  distribution  of  farm  labor  than  continuous 
cropping  to  the  same  crop.  The  labor  necessary  in  producing  oats  and  clover, 
for  instance,  comes  at  a  different  time  than  the  peak  of  the  labor  requirement 
for  corn,  and  fills  in  the  gaps  when  work  would  otherwise  be  slack. 


deducted  from  the  value  of  the  crops,  the  remainder  is  the  income 
to  the  land.  By  dividing  this  figure  by  .05,  we  obtain  the  land  value 
upon  which  these  crops  would  yield  5  percent  interest.  Thus  in  Fig. 
20  are  given  the  land  values  as  determined  by  the  soil  management 
practices  used  on  the  Morrow  plots.  While  they  are  slightly  high,  no 
manager's  wage  having  been  deducted,  they  do  give  an  accurate  ex- 
pression of  the  relative  land  values  of  these  plots  based  upon  their 
productiveness. 

One  hesitates  to  extend  these  results  obtained  upon  the  Morrow 
plots  to  a  state-wide  basis.  In  the  case  of  any  given  crop,  such  as 
corn,  for  example,  the  crop  is  grown  on  many  soil  types.  The  natural 
productiveness  of  these  types  varies  greatly  and  the  response  of  crops 
to  fertilization  or  to  other  practices  varies  in  no  less  degree.  Further- 
more, individuals  differ  so  greatly  in  ability  and  efficiency  that  like 
treatments  and  rotations  on  two  similar  farms  might  produce  very 


1927} 


LESSONS  FROM  THE  MORROW  PLOTS 


135 


different  financial  returns  under  the  management  of  different  oper- 
ators. However,  some  generalizations  which  apply  to  the  state  at  large 
can  safely  be  made. 

The  three-year  rotation  with  soil  treatment  has  produced  more 
than  30  bushels  of  corn  an  acre  a  year  in  excess  of  the  yield  in  the 
two-year  rotation  of  corn  and  oats  on  untreated  land  (Table  3).  The 
two-year  rotation  without  soil  treatment  is  very  commonly  practiced 
in  the  corn  belt.  It  would  not  of  course  be  fair  to  assume  that  this 


I  /Vo  treatment    u£  Manure,  limestone,  phosphate 


Corn,  oats,  clover  rotation 


FIG.  19. — ANNUAL  PROFIT  AND  Loss  FROM  DIFFERENT  METHODS  OF 

FARMING  PRACTICED  ON  THE  MORROW  PLOTS 

Continuous  corn  production  on  the  same  land,  even  with  a  good  fertiliza- 
tion program,  cannot  be  made  profitable  over  a  long  period  of  years.  Alternation 
with  oats  effects  a  marked  betterment  in  the  situation,  which  is  still  further 
improved  by  the  introduction  of  red  clover.  Similar  improvement  could  be 
equally  well  accomplished  by  the  use  of  other  crops  than  oats  and  red  clover. 
(Graph  based  on  crop  records  for  twenty-three  years,  1904  to  1926.  Land  valued 
at  $200  an  acre,  with  interest  rate  of  5  percent.) 


30-bushel  increase  might  be  obtained  on  the  entire  8  million  acres  of 
corn  grown  in  Illinois  annually,  an  assumption  that  would  appear  to 
double  the  state's  corn  production.  It  can  be  said,  however,  that  im- 
proved practices  in  rotation  and  fertilization  would  significantly  raise 
the  acre  yield,  possibly  enough  to  offset  the  reduced  corn  acreage 
brought  about  by  the  introduction  of  other  crops  into  the  rotation. 

Thus  while  the  total  amount  of  corn  produced  in  the  state  would 
not,  in  all  probability,  be  increased  should  the  practice  of  a  three-year 
rotation  with  clover  and  fertilizers  be  generally  introduced,  the  pres- 
ent production  or  somewhat  less  than  that  would  be  secured  on  a 


136 


BULLETIN  No.  300 


[December, 


greatly  reduced  acreage  and  at  less  cost,  while  at  the  same  time  a 
large  area  would  be  released  for  the  growing  of  clovers  and  other 
crops.  Also,  without  greatly  affecting  the  total  production  of  agri- 
cultural crops,  the  quality  of  the  products  would  be  improved,  par- 
ticularly as  feed  for  animals,  because  of  the  increase  in  protein  pro- 


•  No  treatment   u&  Manure,  limestone,  phosphate 
$200  — 

250    — 


zoo  — 


C    ISO     - 


IOO     — 


50    — 


O    — 


Corn,  oah 
ro  fat  ion 


Corn,  oats,  clover 
rotation 


FIG.  20. — How  LAND  VALUES  ARE  AFFECTED  BY  SOIL  TREAT- 
MENT AND  CROP  ROTATION 

This  graph,  based  on  twenty-three  years  of  crop  records 
from  the  Morrow  plots,  shows  how  relatively  low  land  values 
which  result  from  soil  exhaustion  under  poor  management 
are  replaced  by  mounting  values  as  the  capacity  of  the  soil  to 
produce  good  yields  is  increased  thru  good  rotations  and  soil 
treatment. 


duction.  Protein  feeds  are  required  in  balanced  animal  rations,  and 
if  not  produced  on  the  farm  in  the  form  of  clover  or  other  legumes, 
they  have  to  be  purchased,  usually  in  the  form  of  costly  nitrogenous 
concentrates.  Thus  the  economy  of  production  would  be  improved, 
and  the  result  would  be  a  general  improvement  in  the  economic  status 
of  the  farmer.  These  changes,  moreover,  might  reasonably  be  ex- 
pected to  result  in  an  upward  trend  in  land  values. 


1927}  LESSONS  FROM  THE  MORROW  PLOTS  137 

SUMMARY 

The  Morrow  plots  have  been  in  operation  for  fiftv-two  years  and  are 
known  as  the  oldest  experimental  soil  plots  in  the  United  States.  On  one  of 
the  plots  corn  has  been  grown  continuously;  on  a  second  plot  a  rotation  of  corn 
and  oats  has  been  practiced  for  the  entire  period ;  and  on  the  third  a  rotation 
of  corn,  oats,  and  clover  has  been  grown  for  the  last  twenty-four,  years.  Re- 
sults from  these  three  cropping  systems  without  fertilizers  are  presented  from 
the  twelfth  year  of  the  operation  of  these  plots  thru  1926,  or  for  thirty-nine 
years,  and  results  for  the  last  twenty-three  years  are  given  for  the  same  cropping 
systems  with  applications  of  manure,  limestone,  and  phosphate. 

Crop  rotation  has  noticeably  improved  the  yields  over  continuous  corn 
growing.  The  three-year  rotation  has  been  more  effective  than  the  two-year 
rotation  in  maintaining  yields  over  the  entire  period.  The  two-year  rotation, 
however,  has  been  gaining  on  the  three-year  rotation  in  recent  years  because  of 
the  influence  of  sweet  clover. 

Clover  has  been  of  much  benefit  in  the  cropping  system,  both  red  clover 
grown  as  a  hay  crop  and  sweet  clover  used  as  a  green  manure. 

On  the  untreated  land  crop  yields  have  steadily  declined,  not  only  where 
corn  has  been  grown  continuously,  but  also  in  the  rotations.  The  decline  is 
most  pronounced,  however,  under  continuous  cropping  to  corn. 

The  manure,  limestone,  phosphate  treatment  in  all  three  cropping  systems 
has  converted  a  downward  trend  in  yield  into  an  upward  trend.  The  beneficial 
effect  of  the  treatment  has  been  even  more  pronounced  in  the  good  rotations 
than  on  the  plot  growing  corn  continuously. 

Thruout  the  season  the  crops  growing  on  the  treated  soil  are  usually  at  a 
more  advanced  stage  of  development  than  those  growing  on  the  untreated  soil. 
In  corn  this  shows  up  at  husking  time  in  drier,  sounder  ears  than  those  found 
on  the  untreated  land. 

Cropping  the  land  without  treatment  has  used  up  phosphorus,  nitrogen, 
and  other  elements,  and  has  resulted  in  the  destruction  of  organic  matter  by 
decay.  While  these  decreases  in  total  amount  have  been  too  small  to  be  of  great 
significance,  the  decrease  in  active  organic  matter  and  the  removal  of  available 
plant- food  elements  has  been  a  matter  of  much  importance,  being  largely  re- 
sponsible for  the  decline  in  yielding  power. 

By  increasing  the  proportion  of  active  organic  matter  that  can  be  readily 
attacked  by  microorganisms,  the  crop  rotations  and  soil  treatments  used  have 
had  a  marked  effect  in  improving  soil  conditions  for  bacterial  activity,  as  meas- 
ured by  the  nitrate-production  test. 

The  practices  in  rotation  and  soil  treatment  which  have  been  the  most  ef- 
fective in  increasing  the  crop-producing  capacity  of  the  soil  have  also  been  the 
most  profitable  financially.  These  better  practices  not  only  have  increased  the 
yields  but  they  have  made  possible  a  greater  economy  in  production,  an  impor- 
tant factor  in  increasing  farm  profits. 

The  state-wide  application  of  the  better  practices  used  on  the  Morrow 
plots,  with  modifications  necessary  to  suit  local  conditions,  would  result  in  larger 
acre  yields  of  all  crops  grown  and  in  reduced  production  costs.  Moreover  the 
produce  from  the  land  would  be  better  balanced  in  feeding  value  because  of  its 
higher  protein  content.  These  changes  might  reasonably  be  expected  to  result 
in  an  upward  trend  in  land  values  and  a  general  improvement  in  the  economic 
status  of  the  farmer. 


138 


BULLETIN  No.  300 


[December, 


TABLE  8. — ANNUAL  ACRE  YIELDS  FROM  MORROW  PLOTS  SHOWING  SEPARATELY  THE 

YIELDS  FROM  PLOTS  TREATED  WITH  STEAMED  BONE  MEAL  (bP)  AND  FROM 

THOSE  TREATED  WITH  RAW  ROCK  PHOSPHATE  (rP) 


Year 

Soil 
treatment 
applied1 

Plot  3 

Corn 
every 
year 

Plot  4 
Two-year  rotation 

Plots 
Three-year  rotation 

Corn 

Oats 

Corn 

Oats 

Clover 

1879-87 
1888 
1889 
1890 
1891 
1892 
1893 
1894 
1895 
1896 
1897 

1898 
1899 
1900 
1901 
1902 
1903 

1904 
1905 
1906 
1907 
1908 
1909 
1910 
1911 
1912 

None  

bu. 

bu. 
49  .'5 

54.3 
33.2 

29.6 
41.  '6 
47.6 

44  .'4 
33.7 
35.9 

48.0 
40.0 
52.0 
49.8 

43.9 
81.4 
51.7 
93.8 

31.6 
60.4 
34.4 
69.2 

26.6 
44.4 
30.6 
48.2 

bu. 
37.  'i 

37.  "2 
57.'  2 
34."  5 

ii.'s 

56.  "3 

17.5 
22.5 
17.5 
28.1 

30.6 

44.3 
38.7 
60.6 

31.9 

46.9 
33.8 
43.1 

31.3 
51.9 
36.3 
66.9 

52.8 
81.2 
57.1 
80.9 

bu. 

bu. 

tons 

None  

54.3 
43.2 
48.7 
28  6 
33.1 
21.7 
34.8 
42.2 
62.3 
40.1 

18.1 
50.1 
48.0 
23.7 
60.2 
26.0 

21.1 
16.1 
22.5 
19.3 

22.5 
26.8 
27.0 
36.0 

25.3 
32.5 
28.9 
39.1 

28.5 
40.8 
29.4 
56.5 

10.9 
24.8 
15.9 
31.1 

26.4 
30.4 
26.8 
32.8 

32.6 
48.9 
39.1 
60.3 

20.7 
29.0 
23.0 
34.0 

40.0 
64.4 
46.4 
64.0 

70.2 
34.1 

48.6 

65.  1 

22.2 

4.04 
1.51 
1.46 

None  

None    

None  

None 

None  

None  

None 

None  

None  

None  

None  . 

53.5             

None  

None  

34.3 

51.4 
76.4 
67.1 
81.4 

77.4 
91.4 
83.6 
95.8 

52.3 

78.3 
64.9 
88.3 

54.6 

35.6 
45.0 
49.0 
56.2 

38.8 
43.8 
41.3 
45.0 

16.0 
37.8 
25.1 
38.2 

i.ii 

1.36i 
1.88* 
1.49J 
1.60i 

.40+   .52' 
1.72+1.17' 
.90+   .75» 
1.75+1.17* 

1.20« 
1.85« 
1.50< 
1.55« 

None   .    . 

None  

0  .  . 

MLrP.  . 

0  

MLbP..    .. 

0  .  . 

MLrP.  . 

0  

MLbP  

0  .  . 

MLrP..  . 

0  

MLbP  

0  .  . 

MLrP.. 

0  

MLbP  

0.  . 

MLrP.  .  . 

0  ... 

MLbP  

0  .  . 

MLrP.  .  . 

0  ... 

MLbP.. 

0  .  . 

MLrP.  . 

0  

MLbP.. 

0.  . 

MLrP.  . 

0  

MLbP... 

0.. 

MLrP.  . 

0  

MLbP  

'Treatment  on  the  south  half  of  Plot  4  includes  legume  green  manure  beginning  in  1904. 
JCowpea  hay  in  1906.     'Clover  seed  harvested  (bushels)  in  addition  to  hay. 
'Soybean  hay  in  1912. 


1927] 


LESSONS  FROM  THE  MORROW  PLOTS 


139 


TABLE  8. — Concluded 


Year 

Soil 
treatment 
applied1 

Plot  3 

Corn 
every 
year 

Plot  4 
Two-year  rotation 

PlotS 
Three-year  rotation 

Corn 

Oats 

Corn 

Oats 

Clover 

1913 
1914 
1915 
1916 
1917 
1918 
1919 
1920 
1921 
1922 
1923 
1924 
1925 
1926 

0 

bu. 
17.6 
32.4 
21.2 
31.6 

28.8 
37.2 
34.4 
41.6 

37.6 
62.8 
42.4 
69.2 

10.8 
9.6 
11.6 
12.0 

40.8 
60.4 
39.2 
73.6 

13.2 
29.6 
14.0 
35.6 

21.6 
41.2 
26.4 
45.6 

26.8 
52.0 
29.6 
56.8 

16.0 
38.4 
23.6 
46.0 

21.3 
38.5 
27.8 
39.2 

13.2 
32.0 
16.8 
30.8 

27.2 
40.4 
28.8 
35.6 

15.4 
41.7 
22.9 
49.1 

20.4 
33.2 
22.4 
37.6 

6u. 
26.8 
22.0 
31.6 
28.0 

48.0 
80.8 
50.0 
81.6 

44.4 

77.6 
52.4 
85.2 

30.0 
65.6 
31.6 
66.8 

26.8 
68.0 
34.4 
68.8 

16.4 
50.4 
18.0 
42.4 

25.6 
39.4 
27.8 
39.6 

bu. 

32.9 
56.9 
34.2 
59.6 

33.8 
62.5 
41.2 
66.9 

25.6 
53.1 
28.8 
65.6 

36.2 
48.  1 
38.  1 
55.0 

37.5 
56.3 
41.3 
55.0 

34.4 
68.1 

37.5 
68.8 

23.8 
76.3 
21.9 
76.3 

bu. 
29.6 
45.2 
38.0 
50.4 

26.8 
37.6 
28.8 
43.6 

51.6 

69.2 
52.8 
72.4 

45.1 
67.3 
53.2 
73.2 

40.2 
57.4 
43.9 
59.9 

bu. 

33.9 
58.9 
45.3 
62.0 

59.4 
82.5 
77.5 
91.2 

47.5 
73.8 
56.9 
65.6 

50.0 
67.5 
56.9 
65.6 

40.6 
83.1 
48.1 
86.9 

tons 

1.75» 
1.99* 
1.94« 
1.94» 

2.37 
4.05 
2.79 
4.04 

.17+   . 
1.47+  . 
.35+   . 
1.18+  . 

1.67 
4.29* 
1.98 
4.54« 

30» 
80> 
77» 
90» 

MLrP  

0  

MLbP 

0    . 

MLrP  

0    

MLbP   

0  .  . 

MLrP  

0    . 

MLbP   

0    . 

MLrP  

0    . 

MLbP   

0  .  . 

MLrP.  . 

0 

MLbP  

0     . 

MLrP  

0  

MLbP   

0    . 

MLrP.  . 

0  

MLbP         

0  .  . 

MLrP.  . 

0  

MLbP   

0  .  . 

MLrP.  . 

0  

MLbP  

0  .  . 

MLrP.  . 

0  .... 

MLbP  

0    . 

MLrP.  . 

0.  . 

MLbP  

0    . 

MLrP. 

0  

MLbP 

0  .  . 

MLrP.  . 

0  .  . 

MLbP  

0  .  . 

MLrP. 

0  

MLbP  

'Treatment  on  the  south  half  of  Plot  4  includes  legume  green  manure  beginning  in  1904. 
'Soybean  hay  in  1915.     'Clover  seed  harvested  (bushels)  in  addition  to  hay. 
«Hay  contaminated  with  sweet  clover  in  1924. 


140  BULLETIN  No.  300 


Note  on  Origin  of  Morrotv  Plots 

As  is  often  the  case  with  things  of  great  age,  the  exact  date  of  the  origin 
of  the  Morrow  plots  is  somewhat  veiled  by  uncertainty.  A  search  thru  the 
official  University  records  of  these  early  years  has  revealed  the  following 
statements  which  bear  upon  the  subject: 

In  the  minutes  of  a  meeting  of  the  Board  of  Trustees  of  the  Illinois  In- 
dustrial University  held  December  14,  1875  (page  153),  occurs  the  following 
recommendation  by  Manley  Miles,  then  professor  of  agriculture,  referring  to 
the  need  for  rotation  experiments : 

"The  larger  portion  of  the  farm  should  be  cultivated  with  a  variety  of 
crops  in  rotation  to  illustrate  as  far  as  practicable  the  advantages  of  high  tillage 
and  thorough  manuring.  The  advantages  of  a  systematic  alternation  of  crops 
should  also  be  determined." 

In  the  minutes  for  March  10,  1880,  quoted  in  Bulletin  125  of  the  Agricul- 
tural Experiment  Station  (page  327),  appear  the  following  paragraphs: 

"The  Farm  Committee  then  submitted  the  following  report : 
"To  the  Honorable  Board  of  Trustees  of  the  Illinois  Industrial  University : 

"  'Your  committee  beg  leave  to  submit  the  following  recommendations 
from  the  professor  of  agriculture  [George  E.  Morrow]  for  the  coming  season : 
....  'Fifth — the  formal  commencement  of  what  is  designed  to  be  a  long 
continued  experiment  to  show  the  effect  of  the  rotation  of  crops,  contrasted 
with  continuous  corn  growing — with  and  without  manuring,  and  also  the  effect 
of  clover  and  grass  in  a  rotation.  A  commencement  was  made  last  year,  and  we 
are  fortunate  in  having  a  piece  of  land  more  than  usually  well  adapted  for  such 
a  test. 

"  'The  report  was  approved,  and  its  recommendation  concurred  in.'  " 

This  record  would  appear  to  fix  the  date  of  the  official  commenc.ement 
of  these  experiments  as  1879.  In  the  published  bulletins  of  the  Experiment 
Station,  however,  several  references  are  made  to  these  same  plots,1  all  of  which 
point  to  1876  as  the  year  in  which  the  rotation  experiments  were  actually 
started.  These  references  are  as  follows : 

In  Bulletin  8  (February,  1890,  page  266)  T.  F.  Hunt,  assistant  agricultur- 
ist, states :  "Ten  half-acre  plots,  5x16  rods,  have  been  cropped  during  the  past 
14  years  as  follows " 

In  Bulletin  13  (February,  1891,  page  431)  the  same  writer  states:  "Ten 
half-acre  plots,  5  x  16  rods,  have  been  cropped  during  the  past  14  years  as 

follows "     Evidently  this   statement  was  copied   from  Bulletin   8 

without  correcting  the  number  of  years  as  necessary  in  a  publication  of  a  year 
later. 

In  Bulletin  31  (March,  1894,  page  357)  Professor  George  E.  Morrow 
makes  the  following  statement :  "For  eighteen  years  tests  have  been  made 
of  the  yield  of.  corn  on  half-acre  plots." 

In  Bulletin  31  (page  358),  Bulletin  37  (page  20),  and  in  Bulletin  42  (page 
177)  the  column  headings  of  the  tables  state,  concerning  Plots  1,  2,  and  3,  "In 
corn  annually  since  1876,"  and  concerning  Plots  4  to  10,  "In  rotation  since 
1876." 

It  seems  proper  to  conclude,  therefore,  that  the  Morrow  plots  have  been  in 
operation  for  fifty-two  years,  including  the  present  season,  1927. 


'The  Morrow  plot  experiments  are  referred  to   as  "Experiment  23"   in 
all  the  early  records. 


UNIVERSITY  OF  ILLINOIS-URBANA 


